Okay, I mean... wow.
First and foremost, if this shit wasn't in 3D it would be a pretty sucky movie. I mean, on the real, the effects were good, there was plenty of gore and an awesome scene with a chick being chased naked through a car park and motel... but otherwise, it was only so-so.
The brilliant thing is it is in 3D... and that makes it fucking awesome. I mean you have no idea how many asses this movie can kick in just one viewing. I saw it in the cinema, so this wouldn't translate to home viewings... but man, the whole thing was just... so real.
That's the right word for it. Everything on screen just looked so REAL that it became really frightening.