I have mixed feelings about this book. Through the beginning and middle, I was kind of done with this book and the series. The book switches from Tris's to Tobias's perspective every chapter or so, both told in first-person, and both narrated in the exact same way. It was hard to keep up, and Tobias narrated like a girl sometimes. Some flaws in the plots also got to me, and as soon as they stared trying to explain things vaguely scientific, I was turned off. I don't know. Insurgent and most of this one seemed to be lacking something, some kind of heavy planning or something that the first book had but these two didn't. Or maybe I was just over style. I don't know. 
 I do know that if you can't handle some tough stuff (and if you've made it this far, cringing all the way, bless you), you're probably not going to want to finish this book. I was warned before I read it, and I'm repeating it. If you don't deal well with bittersweet endings, don't finish the series. If you're overly attached to the characters' complete, whole well-being, don't finish the series. I'm not saying everyone dies; I'm not saying that the ending is an unhappy tragedy. But there is tragedy in this book, though it does not end on that note. You've been warned. 
 The tragedy, though, is why I'm giving this book four stars instead of three. That tragedy ended up making the book, as heartbreaking as it was. It made it more real, though explanations before that made me realize the events that led up to the factions and what not would probably never happen in real life, which broke me from the spell of the book. The tragedy sucked me right back into caring. 
 This book might not be for those who identify with Amity, who value happiness and peace above all else. It might not be for the Erudite who wants a plausible, thoroughly explained cause for the world the books take place in. But it is for the Candor who wants the truth no matter what. It is for the Abnegation who wants to lose themself in a story of sacrifice. And it is for the the Dauntless who is brave enough to plunge through no matter what.