I don't know about anything else but I love books where the main character can't remember what happens and they believe that they're crazy. There's just something about seeing things through their twisted perspective that just makes the story creepier than if it was being told through someone else.
I loved Mara. Slipping into her head during her descent into madness was absolutely thrilling. Just like Mara, I had trouble telling what was real or a delusion until she figured it out herself and that just made the story because I was constantly left wondering if an event really happened or not. Then thee is Noah Shaw. That boy is just completely swoon worthy. He seems like the typical arrogant bad boy but there is so much more to him. He's actually a pretty deep and caring character. I absolutely did not see the twist with him coming in the story either.
If you haven't read this book yet all I have to say is go get a copy. This is one book that even after you turned the last page it will keep you up at night wondering just what exactly is going on. I will be reading the next book in this series as soon as I have a chance and I am absolutely looking forward to it.