I might have to think on this one a while. I enjoyed the first two books, but the third and final book left me feeling like the story took off in such a different direction. I understand now, now that I have finally read through the series, why people were upset with the last book.
I do get the overall theme. Selflessness. Bravery. Knowledge. Honesty. I get it. I even get where Tris tends to have most of these traits where others tend to only have the one. Something in the second book (or first, it's hard to remember, even now) where Tris said it took transferring to another faction to learn how to be selfless. This was a profound thought. She couldn't do it in Abnegation, where it should have been instinct. It took going to Dauntless, where she would put her body and mind through the ringers to learn how to be selfless. Dauntless, who admire bravery which was closer to recklessness, where bravery and selflessness could collide to make someone better. If I take nothing else away from this series, this will be the one thing that will stick with me for a long time to come.
Over all, I liked the first two. Very much. But the third was hard. And not just because things change and things end. It didn't feel cohesive. It felt like a different story entirely. It made the first two feel so insignificant that I wondered by did we bother to care about what happened if you open it up and everything is not quite on the same level. I almost didn't like how the third was so different from the first two. All of a sudden we get both Tris' side and Four's. I feel like a series should be consistent in the writing. That people shouldn't divide the narration after setting the first two books up. In the end, I guess it all works out.
I will admit, I hated the ending. I didn't feel the hope that the author tried to bring out with the rest, I felt like nothing had changed. There was no ultimate victory. I probably won't revisit this series.