To this day I am still suprised whenever anyone says this. I remember being shocked when everyone else was so suprised at the end when I had assumed he was a ghost for the entire film. I NEVER get twists ever, and yet ironically the twist that is supposedly the most devious of all time is the one I found entirely obvious! Maybe that's why I thought the film was pants.
Although I didn't like how it was revealed, and it's not really a twist, I love how the ending of Tell No One unravells. I won't spoil it.
The end of Identity is pretty nuts actually as well now I think about it. Completely unexepected in every way, no clues whatsoever.