This is sooo close to being a 5-star book for me. So, so close.
A lot of TV series follow the basic "A Plot and B Plot" style of storytelling. Good TV shows manage to connect them thematically and then tie them together into one story by the end. Vinge does this here.
On the macro scale we have the Blight, an ancient, malevolent virus that takes over everyone in its path, human and alien alike. On the smaller scale we have two kids stranded on an alien planet along with a bunch of their friends in cryosleep. The kids are the offspring of some of the explorers who accidentally woke up the Blight and who ran from it once they realized what they'd inadvertently unleashed.
Other reviewers go into more detail about the plot, but that's the gist. The Blight taking over the universe is the B plot, while the castaway kids are the A plot. This is pretty epic in scope. On the one hand we have classic Space Opera and on the other good old-fashioned Planetary Romance. So far, so good.
For me, the real standout part of the book is the kids' adventure among the aliens they call the Tines. This is the sort of thing I read science fiction to encounter: aliens who are different from anything we have on Earth. The Tines are compared to wolves and dogs by the kids, but to me they seem like meerkats. They're run in small packs of 4 to 6 individuals who combine into a larger hive mind. They have vibratory tympanum on their heads, shoulders and haunches that allow them to communicate exactly what they're thinking to each other. Truly exceptional Tines can have 3 members or 8 members and still be a cohesive "person." But usually less than 4 means they're not very bright and more than 6 makes them an unruly mob pulling into too many directions at once.
Vinge's introduction of the concept of these aliens should be taught in writing classes, because he reveals piece by piece how they work over the course of a chapter, and you slowly realize that the "person" you're following is made up of several distinct sub-sentient individuals. It's extremely cool, and one of the best introductions of an alien species I've encountered.
He delves deeply into the benefits and detriments of how such a pack-based hive mind species would work but leaves plenty of unanswered (and unasked) questions so we can speculate on our own. That's great fun.
One of the major detriments to how they link together is that when too many of them are within close proximity to each other, they literally can't hear themselves think. So in instances of battle or simple crowding, it's possible for individual members of a pack to get killed or lost or otherwise cut off from the rest, and it devolves into chaos. Then they become no brighter than an animal and resort to base instincts. A person who loses all but one or two members basically has a lobotomy, and if those individuals join into other packs, the new personality is substantially different than the original.
That's not true in all cases, however, as some individuals are particularly bright or have a sure sense of themselves, which means a duo could merge with three or four others and essentially take over that new pack, reconstituting a facsimile of the original personality. These creatures tend to be dominant personalities, and given the medieval society they live in, become a combination of Genghis Khan or Napoleon, sometimes devolving into Hannibal Lecter, cruel geniuses who bully and destroy those around them.
The bonus is that these strong personalities can basically live for hundreds of years as they assume control of new members who join the pack. Several generations of individual members later they would be different people, but at their core they would be the same. The way around this is via controlled inbreeding, either by using selective breeding of others to create a puppy with particular attributes or to have the members continually have sex among themselves. Which raises the interesting question: is it considered incest if the individuals of a pack have sex with each other generation after generation, or is that parthenogenesis? We'd probably need a new word to describe this activity.
Unfortunately, while such inbreeding creates a centuries-old stable personality, it also results in sickly, infirm or deformed pack members. Who can then devolve into insanity... or worse. See Hannibal Lecter, above.
And such creatures are at the heart of this story. It certainly gives a new spin on politics, as well as dynasties. I would have enjoyed reading an entire novel just examining the various permutations of this shared-mind pack species, but there is that pesky B plot to attend to.
In and of itself, the B plot about the ancient Blight taking over the galaxy is pretty standard fare. We've seen this before in other books with epic scope. I'm pretty sure the guys at BioWare based a large part of the backstory for the Mass Effect videogames on this aspect of the book. There are too many similarities to ignore. I would say they mashed up the overarching idea of the Blight with the Force from Star Wars and created their own universe. Which doesn't bother me, because that's how we get new variations on a theme. After all, George Lucas wanted to make a Flash Gordon movie but couldn't get the rights to it, so he combined the situations and characters of Flash Gordon with those in Akira Kurosawa's Hidden Fortress and added a little sprinkling of pirate movies and Westerns for flavor.
The other aspect of this book that's different from similar space operas is the idea of the Zones of Thought. Basically this is an artificially-imposed limitation to technology. There is a vast area of lower technology comprising the bulk of the galaxy, an area in a ring that allows for higher technology, and finally an area that allows for incredible technology on the outer rim, with no limitations beyond that.
Near the core of the galaxy very little works for long. Errors are introduced and things start breaking. So while you can have anti-gravity and super-intelligent AI in the outer rim, the deeper you go toward the center of the galaxy the less reliable those things become until they quickly stop working.
At first this seems like a pure Fantasy element in an otherwise solidly science fictional universe, but then Vinge reveals that this story takes place tens of thousands of years from now among civilizations which are millions or billions of years old, and basically what we're seeing is an entire galaxy that is living in a post-Singularity time. The implication being that we're currently living under the constraints of the Singularity, which is why we can't get AI to work. But beyond the rim civilizations can Transcend and become godlike.
Too bad for them, the Blight is also godlike. Just not good.
So we get battles in space as civilizations fight the Blight, and battles on the Tine world as these Napoleon and Hitlers battle for supremacy. Meanwhile, our main characters are swept up in both of these conflicts.
As the stories converge it's clear that the solution to the Blight rests with the stranded kids. Unfortunately, this part of the story was telegraphed, becoming very anticlimactic. It means parts of the war against the Blight slow to a crawl because we know what has to happen to defeat it. The only thing I didn't see was the specific aspect of the Zones of Thought. I knew *something* was going to happen there with the various pieces, just not the exact solution, so there's that. But it was annoying waiting for it to occur for 300 pages.
All in all, though, this book is terrific. Could be a bit shorter, but the ideas are so interesting and the Tines are so cool that I didn't mind so much. As I said, these sorts of things are why I read SF in the first place.