Not scary like slasher films or Japanese horror films. This is different. This movie will mess with your head. After watching it, you'll find yourself being kept away by the smallest noises in your own house. They way the film executes its scares is in the little details. Sure, it takes awhile to get to the really crazy stuff, but the gradual buildup will have your heart pounding.
Every time something happened, it had the entire auditorium screaming. And after it ended? People were visibly shaken. I seriously couldn't stand up for about a minute after it ended.
Everyone should see this. It's good filmmaking. I even forgot it was a movie for awhile.