MUST WATCH!
I'll admit I was a little hesitant to watch this one as I thought it would not live up to the hype but I was totally wrong. It takes a bit of time to develop but the story lives up to its hype and is definetly worth watching. There was a particular scene in the movie which made me gasp and others in the theatre as well.
It's a great movie and I recommend it if you love psychological thrillers.