This movie isn't like any of the movies you've seen before. If I had to categorize it, I would say it's an action-mystery thriller. It's not a real horror movie, it's got very little shock value.
The cast does really well, they all play to their strengths from other movies. A lot of twists and turns, although some of them you can see coming a mile away. The movie does keep you guessing as to how it's going to end.
As long as you realize this movie isn't a remake of anything, and you go into it not looking for some scary horror movie, I think you'll enjoy this.