A fairly entertaining, well-written, and fast-paced read but I felt the strength of the climax was diminished because the story hasn't ended. There was a point about a chapter or two before the end of the book that I thought would have been a perfect stopping point for the story. It would have wrapped things up nicely with just enough ambiguities to keep readers thinking about it, without leaving too many holes.
I'm not entirely convinced by the idea of mandatory cosmetic surgery but it's an interesting enough concept and I'm fairly satisfied with Westerfeld's explanations for it. I thought the comment about eating disorders was stupid though, and seemed more like an attempt to include a popular topic in contemporary teen novels, rather than a legitimate reason for people being turned "pretty".