After bouncing off this for years, I got trapped outside someone's house for an hour with nothing in my purse with it. So I read it. I was able to read it in an hour because I ended up skimming heavily. That's why this is not a real review.
A long, long time in the future, in a galaxy far, far away, some humans mess with a library of sorts and create an AI (I think) which kills most of them for reasons that maybe were explained in some part that I skimmed. The ones who escape land on a planet inhabited by the Tines, doglike creatures whose packs of four to eight share a single consciousness. More or less. It's complicated.
The Tines kill all but two of the humans, a kid brother and sister, who each end up with two of the Tine factions. Everything involving the Tines and their weird ways-- they can recreate their selves and alter their personalities by adding or subtracting new members-- is just fascinating, and I loved those parts.
Unfortunately, there is a whole other story, or perhaps several, which bored me to death, involving a librarian and some aliens and a guy named Pham who gets resurrected, and, if I was not hallucinating, messages on usenet. That was the part which I skipped due to unreadability.
Does Vinge ever return to the Tines? I'd happily read a book just about them.