So I saw "Paranormal Activity" with my girlfriend and I have to admit it wasnt that bad. Some quite nice ideas that movie got like the onewith the camcorder which makes the audience to a silent observer in the night while the actors are sleeping and not recognizing the "Activities" they have to suffer!
Still the idea of "the whole movie is a home video and not a movie for cinema" was a blast when "Blair Witch Project" came out and is not that smashing twice and so "Paranormal Activity" is not really new if it comes to that point.
Also the real nice moments of the movie where shown already in the trailer...what really sucked in my opinion. Here the is the link to the tailer on you tube:
All in all id say: If you want to see an entertaining movie with some scary moments go and watch it yourself...but if you expect some hard horror better see something else!