This sequel, which is mostly a prequel, is one of the rarest of happenings in movies: a second flick that's better than the original.
Creepier. Scarier. More intense.
Paranormal Activity 2 provides information that fills in the back story to the first Paranormal Activity, then tells a terrific original tale without becoming a caricature, which happens too often with sequels. The minimalist style only serves to make the film feel more real, and thus more horrifying.
You'll jump, you'll squeal and you'll scream. And you'll have a helluva lotta fun.