I liked this book. It was fun to read, it kept on moving like a thriller should, and I didn't see the big twist at the end coming. All the characters were there for a reason, and all the side plots were too. There were some language and random short descriptions or scenes that seemed to be added for pure "shock" value, but it wasn't overly distracting.
I don't think it was one of the best books I've ever read, but it was entertaining in the way it was supposed to be. I do wish they ended a story the day after they did, but then I probably would have complained about the author wrapping everything up too nicely :P I give the book a 3.5/5.