There is, I'd say, a pretty widespread consensus about the new Who, viz.: that the retooling of the series has been a notable success; that Eccleston was a good Doctor but Tennant is even better (perhaps, some people whisper, the best yet) and that Russell T. Davies is to be greatly lauded for his part in the whole Whonaissance. By the same token the consensus seems to have arrived at a less dithyrambic assessment of series 3. This run, by general agreement, was not quite as good as series 2. Though production values were as high, or higher, the quality of the particular episodes has been very variable; and though Freema Agyeman's Martha Jones has done pretty well as the Doctor's companion, her family, despite getting a good proportion of screen time, have failed to come to life in the way Rose Tyler's family did in the first two series. Then there is the question of Davies's putative godlike genius. What does the consensus say about the six scripts he provided for this series? Could it really be, as many have suggested, that they were the weakest of the lot?

In part this has, I think, something to do with the distortions of hindsight. Series 2 was just as uneven, if we take it episode by episode; but the series finale—splendidly conceived and wonderfully written (by Davies)—packed enough genuine emotional punch in its separation of Rose and the Doctor to cast a rosy glow over the series as a whole. Having Rose's father reach from the alternate dimension to save his daughter's life was a splendid coup-de-theatre. By contrast, the three-episode series 3 finale represented some of the poorest Who writing we've seen in a long while. This fact, combined with the fact that "Blink," the Stephen Moffat episode that preceded it, was so very good, makes it hard to assess the whole series fairly. It leaves the Whofan with the distinct impression that Moffat is a better writer than Davies. Maybe Davies has lost it; maybe the very talented Moffat—who, with "The Empty Child" and "The Doctor Dances" wrote one of the best first-series storylines (the gas-masked children keening, "Are you my mummy?"—you remember the one) and whose Jekyll series is presently generating a positive and well-deserved buzz on UK television—should be given a greater proportion of the scriptwriting duties.

The question, then: is that really a fair judgment of series 3? I wonder if it isn't a trick of perspective, a distortion occasioned by the final trilogy of episodes.

Let's take those last three episodes first, since they're freshest in everybody's mind. It seems clear that in "Utopia," "The Sound of Drums," and "Last of the Time Lords" Davies was trying to recreate the mix of elements that made the series 2 finale work so well: tying together plot elements from across the whole series to cash-in the sense of coherence, and the emotional momentum, the series accumulates, whilst also paying off the emotional interplay between Doctor and companion. In series two he managed to generate tension despite the fact that everybody knew that odd-faced pixie Billie Piper was leaving the series (I for one really thought she was going to die in the last episode). In series three, despite straining with all his writerly muscles, he could not manage the same trick.

"Utopia" was a serviceable episode, and it's a mark of how high our expectations (our, we might say, Whoxpectations—actually, I'll stop doing that now) have been raised that "serviceable" no longer seems enough. The story starts at the end of time, where the oddly unevolved remnants of humanity are gathering to board a rocket that will take them to the titular good-place/no-place. We learn that an elderly scientist, played by Derek Jacobi, is actually the Master in disguise. We learn this because he's carrying a fob-watch of a particular design. In the earlier episode "Human Nature" the Doctor possessed the very same design of fob-watch, into which he had downloaded his true identity whilst he masqueraded as a human to hide from some allegedly terrifying aliens. Mind you, in "Human Nature" the human-version of the Doctor looked like the Doctor, whereas in "Utopia" the human-version of the Master looked like a fruity old British thesp. It wasn't explained why.

"The Sound of Drums" moved the story on in promising ways. The Master steals the TARDIS and bats back to early twentieth-first-century Earth. In a clumsy but jolly satire on the rise of Tony Blair, John Simm's boy-faced villain is elected UK Prime Minister. The drums of the episode's title are the subconscious thrum that have hypnotised an entire nation into voting for a man with a plausible manner, no actual policies and evil intentions. It was a nice touch to make that drumbeat the same quadropercussive duh-duh-duh-der that underlies the Doctor Who theme tune itself (duh-duh-duh-der—duh-duh-duh-der—duh-duh-duh-der—der! der! der-duh—duh-duh-duh-der—). There's also some promising backstory stuff about how a glimpse into the naked time schism turned the young Master on to evil.

But then everything starts to come undone. The Master assassinates the President of the USA, unleashes six billion metallic robot footballs onto the Earth to decimate the population and, like Plankton in Spongebob Squarepants, realises his long-held dream to Rule! The! World! The Doctor is unable to stop him doing this because of a sudden flurry of overly compacted recapitulative plotting. "Do you remember the episode where the Doctor's hand was severed and he grew a new one in moments? Well, here's the old severed hand! Right, OK, so do you remember the "Lazarus" episode, in which the evil scientist developed technology to reverse the ageing process that actually turned him into a monster? Well, I've somehow gotten hold of that machine, and by using the DNA from the doctor's severed hand, and by reversing the reserve-ageing technology, although without turning him into a monster, and without explaining how it is that the Doctor doesn't simply regenerate to free himself from this fate, I'll turn the Doctor into a hundred-year old man! Or at least into a thirty-five-year-old wearing a great deal of latex on his face!" It's all too convoluted, and the execution too hurried, to work dramatically. The fact that this transformation is effected by a stop-motion sequence of the Doctor in various melodramatic poses of agony, like a hypercaffeinated breakdancer, only highlights the fundamental silliness of the development.

"Last of the Time Lords" starts a year later, with the earth suffering under the Master's planktonian jackboot. This episode contains a deal of dystopic moping around in disused warehouses and quarries, and provides us with a further example of the Master's evilness when, by blasting the Doctor with a second dose of Rapido-Age, he turns him into Harry Potter's house-elf Dobby. The climax relies upon a shamelessly rechauffé old cliché, the countdown to disaster, which is as creaky a plot device as you might expect. And then the whole story effectively collapses into spilt blancmange as the aged Doctor is rejuvenated by the entire population of the earth repeating the word "Doctor" in unison. When it comes to explaining precisely how this deus ex machina is effected, you can almost see the blur of Davies's scriptwriterly hand waving: something about the Doctor spending a year tuning into a telepathic wavelength (did you know he could do that? Can you think why it might require a whole year's preparation?) and some orbital satellites. But none of that matters, because it's too painfully obvious that we're actually being served a version of that moment in Peter Pan where Tinkerbell is resurrected by virtue of everybody in the theatre crying with one voice "I do believe in fairies!" Time is then reversed. This is effected by having Captain Jack—perhaps the most fantastically annoying character ever to appear on Who (and that's really saying something)—dismantling the "paradox machine" that the Master had erected inside the TARDIS. In "The Sound of Drums" we were told that even to tinker with this machine could destroy the solar system, so it's perfectly in keeping with the gay abandonment of plot logic that Jack shuts the device down by spraying it with machine-gun bullets. Thus a whole year's global carnage and suffering is magicked away (although, illogically, not for the main cast), a most lame and impotent ending that simply reeks of cheating.

Nothing more is said of the time-schism, a gaping missed opportunity. The Master's Eva Braun-esque wife suddenly ups and shoots him for no very good reason, and the Master then elects to die rather than regenerate, apparently just to spite the Doctor, which is the Platonic Form of cutting one's nose off to spite one's face. The Doctor gives him a Darth Vader-style Viking cremation (and when, exactly, did Doctor Who get into the business of making the funeral arrangements for defeated enemies?), after which the Master's ring is picked out of the ashes by Person Unknown. Rash, I'd say, to end the series with a visual quotation from 1980's Flash Gordon, a film that failed in so many ways, not least in its intention to set up a whole series of profitable sequels. The whole episode comes over as more than silly; it's silly-puerile.

But hold the phone. This question of puerility is, of course, the key one. As the Dobby-version of the Doctor was placed in a cage, I found myself wondering whether this was a deliberate allusion to the Sybil in Petronius's Satyricon, immortal but continually ageing, eventually so shrunken that she was kept in a bottle (this is the passage Eliot uses as the epigraph to The Waste Land: and when the boys come to ask her "what do you want?" she replies "I want to die"). But by the end of the episode it was clear that Davies was aiming at a lower age group. And that gave me pause. Had I so overwritten my experience of Who with pretentious adult expectations that any childishness in the show had become intolerable to me? Was I really criticising Who for being a kids' show?

When you put it like that of course it's obvious. Not only is Doctor Who a kids' show, its great glory inheres in that fact. In one sense the large adult fanbase it has accrued is an encumbrance to its proper functioning. My five-year old daughter watched "Last of the Time Lords" in a pleasurable agony of dramatic anticipation and excitement; only the fact that the sofa in our house is set against the wall prevented her from hiding behind it. She found the resolution thrilling and utterly satisfying. It ought to go without saying that fans—actual children or adults in touch with their childish hearts—will not be bothered by a Peter Pan ending, and are unlikely to mourn the fact that allusions to Petronius Arbiter and T. S. Eliot aren't more thoroughly worked through. Kids are not cynical jaded old hacks like me. There's a freshness to their spirits that the show captures precisely.

So this, it seems to me, is the nub of it. My immediate revulsion was founded upon a kind of category error. Week by week I had been talking myself into a negative frame of mind about Davies's scripts; but looking back I find myself wondering whether my animadversion was actually a coded annoyance that he was writing for a younger demographic than me (write kids' entertainment in a kids' show? The cheek!)

Episode 3, for instance, "Gridlock," is set on a future version of the Earth in which the entire population of the world lives in flying cars all of which are stuck in an eternal traffic jam, going nowhere and with nowhere to go. As worldbuilding it makes no sense at all: to try and imagine how such a society might actually function is to see at once how daft a notion it is. Throwing in giant mutant lobsters lurking in the misty depths and devouring motorists foolish enough to take short cuts via the lowest levels (short cuts? whither? why?) was a pretty desperate attempt to inject dramatic tension into a story that was by virtue of its own premise necessarily stagnant. But for all that, the episode actualises a conceit with genuine imaginative purchase, and one with particular resonance for young kids. It taps into the common childish torment: being stuck in the back of Mum and Dad's car on the interminable journey to Gran and Grandpa's, staring out the window at the gridlock and wondering if you're ever going to arrive. If it lacks deeper sense, then so does the whole process of locking yourself in a small car for hours and hours in order to get to a weird-smelling house you don't even particularly want to visit.

"Daleks in Manhattan," similarly, smacked just a little of Junior History Channel ("Once upon a time in America there was a thing called the Great Depression; and a lot of people who couldn't get work lived in shanty towns called Hoovervilles..."). But that's not necessarily a bad thing, and the story certainly rattled along. The Doctor and Martha uncover a strange Capitalist conspiracy centred on the Empire State Building and connected with a number of bipedal pig-humans running around the sewers. These homo baconis were pitched about right, actually; vulgarly scary and thrilling, and the ending wasn't too cosy or easy. In fact the only real false step in the whole double-parter—apart, that is, from all those British actors assaying American accents of varying degrees of implausibility (actual American actors couldn't be hired because...?)—was its supposedly monstrous pay-off. The "evolution" in Helen Raynor's second-half "Evolution of the Daleks" consisted of a hybrid half-Dalek half-human, which was almost exactly one tenth as scary as the producers thought it was. The half-Dalek half-human, in fact, was worryingly symptomatic of a production team that had forgotten what makes things scary: not what the audience sees but what it imagines. There's a reason why The Turn of the Screw is more terrifying than those 1950s monster movies with actors running about with rubber cacti taped to their heads. What we don't see summons the monsters of our own imagination; what we do see replaces them with a vision that never can be as scary and probably will look as lame as the tentaclecephalic monument of too many hours in make-up at the heart of this episode. But overall the two-parter was a decent and entertaining story.

Similarly Davies' other script, the series opener "Smith and Jones," did its double-job of telling a standalone SF story and introducing new companion Martha Jones pretty well. The worst that could be said of it was that it seemed a little over-familiar—the monstrous alien hiding inside a chubby, snarky human form; the clumpy aliens resembling terrestrial wildlife (here rhinoceri). But it had a brisk little narrative arc, and did some interestingly kid-pitched thematic things with the whole medical-Doctor/Doctor-Doctor parallel by relocating an entire hospital to the moon.

The other episodes were uppy-downy, which is what we might expect in a long running series like this. However delightful it must always be to see TV SF being written by somebody called Roberts, the second episode "The Shakespeare Code" (by Gareth Roberts) was more misfire than on-target. The Doctor and Martha go back to meet the swan of Avon, played by Shameless actor Dean Lennox Kelly who, in what might have been an in-joke too far even for UK audiences, performed the role with a Shameless-style swagger. The conversation hit all the most obvious gags: quoting Shakespearean lines at Shakespeare before he'd written them and having him go, "That's good, I'll make a note of that" was the sharpest it got. The drama, too, was rather underpowered: an evil bird-like race called the Carrionites, trapped in some other-dimensional prison, were on the verge of being released by a magic charm spoken on stage at the Globe. Puppetry was used to render the Carrionites, with the result they were about as realistic, and about as frightening, as Gonzo from the Muppets.

Then there was Simon Greenhorn's "The Lazarus Experiment," in which the improbably-named Professor Richard Lazarus (played with galumphing melodrama by Mark Gatiss) invents the aforementioned reversing-ageing machine and turns him into a younger version of himself. This arrogant young man has the added twist that, like a meat-Transformer, he unfolds into a much bigger creature at moments of stress. Martha's family are shoe-horned into the story higgledy piggledy and to no very good effect. The whole package failed to accelerate my pulse by so much as a hemidemisemiquaver, and my five-year old kept wandering in and out of the room. And then there was Chris Chibnall's "42," a brave but unsuccessful attempt to realise a sort of mini-24, as a spaceship hurtled towards doom in real time. Characters were introduced and killed off, but since we had almost no time to get to know them it was hard to care about their demises. The tension was undercut by our certainty that the Doctor and Martha would survive.

But if a few of the episodes were sub-par, three of them were absolutely tip-top: Paul Cornell's two-parter "Human Nature" and "The Family of Blood," in which the Doctor becomes a human schoolteacher in England in the early 1910s; and the best episode of all, Stephen Moffat's diamond-sharp "Blink."

Cornell's two-hander was an adaptation of his 1995 Sylvester McCoy-flavour Who novel Human Nature (the BBC have now made this available as a free e-book) and the joins hardly showed. On the downside we had, at the beginning, to swallow the idea that the Doctor might wipe his own memory and take human form in order to hide from a bunch of not-overly-scary aliens rather than just confronting them like he does in almost every other episode of the series. The reason for this behaviour given at the end of "The Family of Blood" is that he acts from mercy; letting them die naturally, so as to not be compelled to punish them himself—a dodgy premise, and (given how much carnage the aliens wreak whilst he's hidden) one that, I thought, smacked of abdication of responsibility by the Doctor. But once you accepted that, there was a great deal of fun to be had with the Edwardian Bourne Supremacy storyline (the if-you-will Bourne Whopremacy...no, wait, I promised to stop doing that).

As for "Blink"; well, the more I think about that show the better it gets in my memory. It's the very definition of a good episode: a clever and haunting premise, witty and effective dialogue, tight and ingenious plotting, and a thoroughly satisfying pay-off. The premise is that aliens taking the form of statues want to get you, pitch you back into time and steal the life energy that you thereby vacate. But these statues can only move when you're not looking at them; don't turn your back on them, and if you are facing them don't so much as blink. The statues were actually scary, unlike the tentacle-headed homo dalekus; and it was an inspired idea to focus the episode on a human—Sally Sparrow, played very attractively by the very attractive Carey Mulligan—and to push the Doctor to the margins of the story. Every series has a "Doctor-lite" episode of course ("Love & Monsters" was the S2 one); but it's still a testament to Moffat's skill that he turns that to a strength. The conversation in which the Doctor explains circumstances to Sally is conducted via television, Sally in the room, the Doctor speaking onscreen via a pre-recorded DVD, was nothing short of brilliant (Moffat managed to make this talking-to-the-TV thing work twice and then to explain how it works perfectly plausibly). The worst I'd say of "Blink" was that it needed a longer slot than 45 minutes to properly develop some of its elements—the near-miss relationship between Sally and her dozy admirer Larry Nightingale for instance. But that is to complain, in effect, that the episode was so good I wanted more of it.

So, a series that, despite some weaker episodes, contained not only many memorable moments, but also a couple of the strongest episodes in the show's history. By what right would we give that anything less than two thumbs up? On reflection I've come to the conclusion that my initial disappointment at the end of "Last of the Time Lords" coloured my apperceptions of what was, overall, an above-average series. Take that, Consensus.

Adam Roberts is a writer and critic of SF. He lives a little way west of London.