I'm sure you all have heard the story of the individual suing the makers of Drive for delivering an incredibly misleading trailer. However, this person should have waited a couple of weeks to see Paranormal Activity 3, as nearly half of the scenes in the trailer, including some of the main ones that make the trailer scary, are not in the actual movie. Beyond that, there are huge gaps in storyline, and an ending that lacks the punch of the first two, despite some nice thrills along the way.
The film opens up with Katie and Kristi as adults, where Katie drops off some old boxes that contain tapes from their childhood. Then we see a scene where we find out that the tapes were stolen (during part 2), and eventually we as the audience start to watch these tapes from their mother's boyfriend Dennis of a couple weeks, and see how the demon haunting began. We don't know why these tapes are being shown, we don't know who is sharing them with us. And while that may add some mystery to the madness, it is also a frustrating plot hole.
Some of the rules of the game have changed, as activities happen in the daytime as well as night. But other than that, the same formulaic happenings occur, slowing stair-stepping scenes to the supposed grand finale. But in this case, some of the scares don't add up, and there seems to be less continuity and flow than previous installments.
Now I don't want to spoil the final scene, but let's just say, that it is confusing (I mean I got it, but it wasn't as clear as it should be), and by the final shot it is anti-climatic. When the final scene goes black, all of my friends and I were suddenly asking questions most of them revolving around a central theme: What about that scene in the trailer? As at leat four that we mentioned off the tops of our heads were simply not in the film, and instead of leaving the theater shaking with fear, we left frustrated that we paid to see something that simply wasn't there.
In the end, there were a few nice chills throughout the film, but they cannot erase the huge plot holes, the misleading trailer, and the disappointing final shot. Furthermore, I think that the novelty of the original film is wearing off, as after now three installments (and a fourth one in the works), the gimmick is getting derivative, and in the end all I feel is dullness and apathy.