Incarceron has one of the most fascinating worlds I've ever read about. A futuristic society that has chosen to mire itself in the past, this book often has the feel of a fantasy novel, but throw-away details of advanced technology assure the reader that this is, in fact, the future. And what a well-built one! I'm usually more interested in characters than world in my fiction, but in this book the worlds of Outside and Inside, the real world and Incarceron, only draw me to want to learn more about how things came to be the way they are and how things might change in the future.That's not to say that the characters aren't good. Indeed, I found them all to be pretty stunningly complex for a YA novel. The heroes are sometimes selfish, the bad guys are sometimes sympathetic, and most of the characters exist at a sort of mid-range place of selfishness and kindness, thoughtlessness and thoughtfulness that I think mirrors real people in a way that much fiction doesn't, especially in YA and speculative fiction. The dual points of view, one person on the Outside working in and one on the Inside working out, both of them struggling to understand the nature of Incarceron from utterly different standpoints, worked really well in this book, and the characters' flaws didn't hinder their likability, for the most part.This book was definitely a page turner, fast paced in a good way. I devoured this book in less than 24 hours, and I'm very excited to read the second, Sapphique. Despite the fact that I read this in the first days of January, I'm going to sneak it onto my shortlist of best books read in 2010.