Well, I'm going to be in the minority for this one - always a hard place to take in today's book world (especially where anything John Green is related).
I liked the book, I just didn't like it quite as much as I had expected based on all the rave reviews and talk surrounding it.
Paper Towns started out quite well - quirky, interesting characters and some action-packed, intriguing events to get things rolling, but I quickly grew tired and bored of all the searching and things seemed to become somewhat redundant. There was some redemption towards the last 3/4 of the story, but never enough to cure the somewhat bored feeling I had with the book.
John Green is a great writer and he really can create dynamic, fun, quirky, intense characters and he did so here. I loved the characters, though I felt Margo Roth Spiegelman was a bit less quirky and a little more selfish than I originally had thought - I don't think she was actually very deep at all by the end though she originally appeared to be quite an intriguing young lady.
The point of the book, or at least the one I caught onto, wasn't lost on me. We do tend to put people in buckets. Buckets we have constructed based on very thin, outward views we have of them, and that isn't fair. We generally are not the face we put forward, at least not completely. There are always layers and getting to those layers isn't always pretty and we most certainly don't always find what we think we might.
So for the characters and the premise, I did enjoy the book, but I didn't enjoy it quite as much as I had hoped due to some lag and redundancy in the story.