I really liked it, but I didn't like too much Tris in this book. 
 I know she felt guilty about killing Will, but she kept whining, and in spite of vowing to herself to never lie to Tobias again, she kept doing it throughout the book, in the mask of 'for the grater good'. 
 I couldn't buy it. 
 Everything could have gone better if she told Tobias she was going to do those things, instead of keeping it secret from him; after all he's divergent too.