Paranormal Activity 2
Number-based systems are dumb.
Continues the same concept displayed with the first entry without really losing anything. Connects the two movies with a sensible plot, given the circumstances. Not as creepy or pervasive as the original but it scores points by being mean to a dog, it's always easy to make monsters seem more monstrous by assaulting some poor little pooch.
Not as scary as the first, but still very much worth watching.