I just got back from seeing it and was going to start a thread on it.
HOLY FUCK.
it's not cheesy, Hollywood, amusing, entertaining, funny, or any other word you'd use to describe a movie.
It sinks deep into your psyche and plants a seed of terror that doesn't leave. I have never been so scared in my life..I was honestly shaking and near tears the sensation and sheer absolute terror was so overwhelming.
It's not even a movie. I know it isn't real, but how they did it makes your mind think it's 100% real. No credits, no opening scene..it's just BOOM, and the footage rolls up as if the actual camera was retrieved from the scene, and plugged in at the theater. It's so simple.
Don't judge it when you haven't seen it, either. I had mixed thoughts going in, but coming out I was completely blown away.
I now have a greater respect for the power of demons (though I don't necessarily believe in them),
and won't sleep for a month.
It's not like any other horror movie I've ever seen..and I've seen a lot.
In most horror movies, you know what's going on, it's all defined. You have ghost, or a serial killer, or a deadly zombie disease turning people into savage beasts..
But in Paranormal Activity, you're left to judge from the crude framework of authentic patchy pieces of terrifying footage that are seem 100% real. The acting is perfect, and everything seems real.
Another thing that made this movie great (and bonechilling), was the fact that there was no music or outside sound added. There is no ominous high pitched violin music when something is about to pop up, there is no dramatic music when strange things happen, it's just the footage, and nothing more. As if you are right in the room with them.