From what I can say is the movie isn't scary (I went to the actual theater where they blast off the sound). 90% of the trailer does not happen in the movie. There are a few improvements from the last 2. It takes you into the action meaning they dont show things at a angle from a tri-pod most of the time when the camera is being taken from it and showing things happening while the person holding it walks around and such. There are 2 noticeable mistakes. 1.The movie takes place in 1988 and is filmed in widescreen when widescreen home cameras didn't exist yet to my knowledge. 2.They mentioned the toast with Jesus's face on it when the first one reported was much later in that time. The last 20-15 minutes They said it will mess up your life. It didn't, it just gives you no idea whats going on but the little plot twist was alright. The ghost/demon of Paranormal Activity Spoiler It's name is Toby, it growls, and you still dont see him yet. Just to clear this up there will be a 4th Paranormal Activity coming next year. I really hope the 4th clears up unanswered questions and lets us see the ghost/demon or at least a glimpse of it.
