This book just destroyed me. I am completely traumatised. 
 So, yes, it's good! 
 I wasn't entirely convinced by Divergent, but stuck with the trilogy because the action & writing were good enough to allow me to suspend my doubts. The good news is that this continues, and also this climactic book in the trilogy does explain a lot of the holes and questions I had lingering from the first two. The set-up is rather different, as we leave the city of the first two books for a new area, with new characters and challenges. We also get Four's viewpoint in this book in addition to Tris. There are points where the change in direction left me a little cold, without the real engagement with the consequences I had in the first two books. However, this passed as the action, casualties, conspiracies and doubts about who to trust continue to mount up. Tris and Four both face revelations which change how they think about themselves, each other and their friends. 
 The climax of the book (and the triology) is absolutely harrowing. That's as much as I can say without giving spoilers, but I said in my review of Divergent that Roth doesn't pull her punches when perhaps another author would, and the same can most definitely be said of Allegiant.