(Um … please ignore my previous comments on this subject.)
I will not be seeing Paranormal Activity 3 this Halloween. Not because it’s bad or unimportant. I think 2 was very well made. I cheer for the series and enjoy overthinking it. But it has a very basic problem.
You can only do this once.
Paranormal Activity begins full of mysteries. Then it slowly reveals them. Then it ends. Resolving all the mysteries. "Resolving" with a capital "!". Those mysteries are resolved as fuck.
For this reason, all that’s left is to flesh out the backstory. Both 2 and 3 are prequels. We know everything. We know who survives, what the spook is, and what it will ultimately do. Heck, from the setting of #3, we know what happens to the house. We know what they keep from the house. This story is so spoiled I could fill out the insurance claims.
The choices they made in the first movie were good. But they were one-movie choices. Now they can manufacture the creepiest setups and the shockiest shocks anywhere, but it’s like a haunted house you’ve already walked through. You can’t get back the ignorance, so you can’t get back the fear.
Such is life.