I love the progression in this movie as the happy family slowly grows mistrustful of their house and then the demon swiftly moves from toying with them to serious business.
Part of enjoying these films relies on suspending your rational and giving into the belief that this is real fotage you're looking at.
The first movie actually made that alot easier. Paranormal Activity actually had me worried about the activity within the house; the footsteps, the stomping- the demon seemed alot more malevolent.

Paranormal Activity 2 relied mostly on shocking the viewer, and even in this regard, the shocks were few and placed toward the end of the movie.

Speaking of the end; the part of the movie that occured after Micah from Paranormal Activity 1 died was terrible.
It messed up the ending where Katie Featherton died (which was the better one)
All it did was give a weak closure reminiscent of urban legends that tell you the killer is somewhere out there.

The first of this series cost $15,000.oo to make, this one cost #3,000,000.oo....... Someone is walking around right now with $2,985,000.oo in their pocket.