I just read this book, and it was pretty good. I didn't love everything about it, but I was engrossed within a few chapters and wasn't able to switch to a different book.
It's a dystopian future, with a factionalized community living in the Chicago area, divided into "tribes" or groups based on the virtues that they prize above others - Erudite, Dauntless, Amity, Candor, and Abnegation. The main character, Beatrice (who renames herself Tris), lives among the Abnegation, but switches to Dauntless when given her choice. She struggles to survive the training, and succeeds in the end, only to uncover a plot to disrupt the factionalized system and take over the community. It's kind of an interesting twist, the way that the community is divided. I also like the bizarre and cruel way that the Dauntless faction trains its recruits and prepares them for the life they will lead. I like that there are a lot of unanswered questions left for future books, and I might be curious enough to pick up the second book and continue reading. But I'm not sure that this is anywhere near as interesting as the books that are becoming the gold standard for me - Hunger Games, the Chaos Walking series, and Fablehaven. (Maybe Lightning Thief and Harry Potter belong in there too, but on a different level.)
It's surprising how many YA authors are trying to recreate this kind of book - I don't know if it was Harry Potter, Hunger Games, Twilight, or some other series that really pushed publishing and authors to consider this genre. But it's exploding. I can't keep up.