The trailer for this movie is very effective. With the spooky soundtrack and the footage of something unseen moving the covers, it looked so scary that I did not want to see it. But reviews I've seen are so polarized - it's either unbelievably scary or not scary at all.
What I liked about the film was that they chose to use the viewers own imagination rather than special effects and cgi monsters. More filmmakers could use the lesson that what we don't see is often scarier than what we do see. Also they stuck to the concept that this was home movie footage shot by this couple and did not add spooky music to influence the mood.
Now what I didn't like was that it is exactly like watching a friends home movies. It's boring, pointless and only interesting to the person who shot it. Plus Micah is a dick. He's more interested in documenting what is going on than in making sure his girlfriend is okay. He comes off as insensitive, uncaring, and having no respect for his girlfriend's feelings, especially in regards as to how to deal with the supernatural force that is tormenting her.
I saw this on dvd, not in the theater, and the movie had an alternate ending. Afterwards there was video footage from a theater which showed the theatrical release ending. All I can say is that they were smart not to have the alternate ending. Even though it is almost the same, it is so unbelievably lame. It's a cliche which you can't believe is happening.
To sum up, none of us were scared, but I think if seen in a dark theater it would be creepy. But mostly it's like watching someone's boring home movies where you keep praying for something to happen.