I have a love/hate relationship with Peter Hamilton's books. He's very adept at introducing interesting technology and making a faster-than-light society plausible but, as with a lot of these hard-science, libertarian SF authors, he badly needs an editor. I was skipping over multiple pages of irrelevance in both this book and its prequel, Pandora's Star. He also has far too many "main characters" who (despite 800+ pages) never seem to come alive. They all speak with essentially the same voice. And when he tries to individualize someone they come off as badly stereotyped '60s era hippies -- come on, does anyone seriously say "dude" in the real world much less the imagined future of the 24th century? And why is Hamilton so obsessed with sex with young (or rejuvenated) women?
Hamilton's treatment of virtual immortality is hit and miss at best. On the one hand, the innate conservatism of an immortal civilization is well developed, represented and believable. On the other hand, the dynamics of the relationship between "old timers" and "first lifers" is unsatisfactory. In four centuries, for example, NO ONE has even attempted to unseat Nigel Sheldon from his position as head of the Sheldon dynasty? Perhaps the Commonwealth's continual expansion is the safety valve but even here, the government (controlled by the eternal heads of these dynasties) controls it. Another point that is brought up briefly is why would anyone want to live forever if their life didn't change -- I mean the characters of a novel (almost by definition) are dynamic, go-get-'em types but most people just plod through their lives and then die. Why would anyone want to do that for lifetime after lifetime?
The aliens are OK. The problem with them (and this is true of nearly every SF story) is that they tend to be one dimensional -- they're all of a singular type and all too often they really do just act like human beings with weird make up. (This is a problem in fantasy stories, too.) On the plus side, I do tip my hat to Hamilton for not allowing the humans to save themselves with an alien "deus ex machina." Ozzie's adventures in "Wonderland" (i.e., the silfen paths) do bring him to the adult silfen and he does find out the origins of the Dyson barriers but the knowledge doesn't really help anyone defeat the Primes.
Overall, if you started with Pandora's Star, you probably should finish the journey with Judas Unchained. If you haven't started down this "silfen path," I recommend Alistair Reynolds, Tony Daniel or Iain Banks. They write similarly grand space opera but are better at it than Hamilton has proven himself to be to date.
