Whenever I review a new film too extenvely, I end up inadvertently throwing some spoilers in there, so I'll keep this brief:
Go see "Paranormal Activity 3". This installment is better than the first 2 (both of which I enjoyed) in almost every ngle way. The scares are bigger, the cameras-set-up-around-a-house premise is carried off with an ingenious oscillating new wrinkle, and there's more character development to boot. "PA3" has the added benefit of making "PA2" look even better
in retrospect by following through on things that film hinted at, in a way that is scarier than it sounded at the time. My only (minor) complaint is that there were a couple times where it really didn't seem like these people would keep filming, but there are potential character-based arguments that could be made to explain why they did.
Overall, I was extremely impressed by this film. It may even be that rare gem that I see in the theater twice.
For those of you who are sticklers for rating systems, I give "Paranormal Activity 3 " 4 and 1/2 out of 5 stars.