Once the action really started, though, I was reading nonstop. The action is really what got me hooked in the first place. That and the Tris/Tobias love story. They're both still teenagers, but their relationship is at such a great level and i just LOVE IT.
Then comes the ending! I had an idea of what happened due to all of the hints left throughout the book, but just hearing it be said and what came after was still shocking.
Overall, I loved the book. It's great, though not as great as Divergent.