Nathaniel Katz revisits Vinge's A Fire Upon the Deep, and finds it all comes down to the ideas:
Despite all that, though, Vinge’s characters, and even his plots, are well overshadowed by his ideas. The excellence of each and every one of his humanoid and alien creations comes from their reactions and actions in their extraordinary and inventive situations, and the joys of his flashy plotting come from the way that it interacts with his cosmos. So, once just about all’s explained and understood, or at least as much as it ever will be in the novel’s pages (or ever could be by our Slow Zone minds?), a bit of the excitement leaves the affair, and the broad strokes of the novel’s ending aren’t too surprising, even if the particulars might be. Tied into that is the fact that we only get to viscerally feel the aspects of the climax that take place on the Tines world, a shame because it’s in terms of the larger galaxy that the unexpected aspects of the ending really hit. But, for all that, the ending’s still a damn fine one, a shade disappointing only for being merely very good at the end of such an exquisite work.
Matt Hilliard considers the novel's villain:
Except Vinge takes boring Lord Steel and throughout the novel puts him in situations that force him to play against type. Lord Steel wants nothing more out of life than to be the boring Bad Guy, but the only way he can harness the power of offworld technology for world domination is by convincing a young human boy he’s actually a good guy. Rather than twirling his metaphorical mustache, he has to endure hugs and act as a surrogate parent for both the human boy and a young Tine. Worst of all, he has to do this under the gaze of his feared master, Flenser…kind of. If Flenser was really present, he’d be in charge and Steel would be comfortable in the familiar role of chief minion, but Flenser is only kind of present. Trapped by traditionalist enemies before the novel began, Flenser took the radical step of breaking his six member pack into three pairs that were forced into three other packs. Avoiding detection, one of these packs, originally a schoolteacher named Tyrathect, returned to Flenser’s stronghold as the starship crashed. But the others did not survive, which means Lord Steel is still in charge, struggling to play the part of gentle father figure while someone who is two thirds schoolteacher and one third history’s greatest monster watches and critiques his performance.