At first, I couldn't decide if I liked Sundiver or this book better. The former has a superior mystery, and arguably a superior plot. Startide Rising, on the other hand, is more satisfying on the subject of "uplift" itself and better portrays the multitudinous horrors of Galactic society.
After considering my quandary further, I decided to throw in behind Sundiver. My fellow Goodreads reviewers seem split on this question, but the more I think about it, the more I'm certain. As much as I like what Startide Rising does to further the uplift concept central this series, its story and characters are muddled and dull.
We get a very sparse look at Galactic society in Sundiver, with singular representatives from a few species. Startide Rising rectifies this by showing us entire fleets from a variety of species, all of them pursuing the Streaker in attempt to take the information it has discovered. We get to meet the matriarchal Soro; the vicious Tandu and their reality-altering client species, the Episiarchs and the Acceptors; the Jophur, the Thennanin, etc. Brin's quite creative when it comes to species names and behaviours. But if Sundiver was a drought, then Startide Rising is a deluge: there are just too many aliens, and we don't spend enough time with any one of them. The results are thin, one-dimensional antagonists like Krat, fleet-mother of the Soro contingent. The Galactics are once again bogeyman instead of credible players.
This tendency of Brin's to overindulge is obvious planetside as well. There are just too many characters, too many points of view. At times this results in a total breakdown of the coherence of the story; I found myself unable to tell what was happening any more. Primal Delphin, Trinary, Anglic, whatever language the Karrank% spoke . . . too many symbols, and all very surreal. This is not an easy book to read, and while that's no disqualification on its own, it means the reward for reading it should be proportionally greater.
Yet I found Startide Rising lacklustre in its resolution. Once again, Brin explores what it means to be human by showing us how aliens (in this case, Uplifited dolphins) adopt human-like behaviour, including belligerence. Takkata-Jim's mutiny is a perfect example of this. The dolphins' journey toward sentience has been one away from the "Whale Dream" that prevents cetaceans from logical, abstract thought so critical for tool use (and thus spaceflight). While many of Takkata-Jim's mutineers revert to more primal instincts, Takkata-Jim himself behaves more and more human as the story progresses (not always to the benefit of our protagonists).
No matter how great its themes, however, Startide Rising is still burdened by its story. As with the antagonists, the main plot points begin multiplying until it's hard to tell what matters any more. There are metallic life-forms, pre-sentient aboriginals, voices telling Captain Credeiki what to do, etc. It just happens that after stumbling on a derelict fleet—setting off this great galactic chase—Streaker hides on a planet that has more mysteries than anyone could have imagined! Alas, we do not learn the ultimate fate of the Streaker crew or the inhabitants of Kithrup! This book provides many questions but precious few answers.
And so the moral of Startide Rising comes not from its themes but its execution: less is more! David Brin's "uplift" concept is so intriguing, so deliciously seductive in its shiny science fiction package, that it's enough to sell me on the series. But I'm finding the experience less fulfilling than expected, because the books just try too hard. Keep it simple Startide Rising does not.