So, yeah, I finally went and saw Paranormal Activity tonight. The short of it is that it's a slow-paced movie that gets increasingly creepy and finishes big. While I think it's probably a best-for-video movie - to the point that I think the film would actually be creepier viewed at home - what you don't see at home are the people who leave the theater because the movie's freaking them out too much.
I went in to the theater knowing pretty much what to expect. If you've seen a full ad the for the movie, then you know what to expect. That's kind of a bad thing. There's not a lot happening in the movie. The majority of the film happens in the couple's bedroom - them sleeping or reacting to the paranormal activity, however. Otherwise you get some pretty stereotypical horror/suspense movie characters. Where the movie really succeeds is in its use of home-video style camera work. I read a while ago about how this use, kind of putting the viewer in the viewfinder, breaks the fourth wall. I don't know if I'd go as far as to say that, but it does make the movie feel more intimate that your average big-budget fare.
Outside of the movie was another thing all together. There were some annoying movie patrons nearby - a couple who wouldn't turn off their cell phone, some who wouldn't stop talking - but I was kind of hoping I would get to witness some reactions like you see in one of the advertisements. I wasn't disappointed. About 15 minutes from the end, a couple left. Then another left. Then another. It was too funny. Some who were left who were obviously close to leaving gave some pretty loud "OH DAMNS!" and interesting screams. That was worth the price of admission.