Not only is the comparison to proper film trilogies (The Bourne movies, Back to the Future, or Star Wars, to name a few) laughable, but considering conventional studio logic, box office success (say hello to your #1 movie, Canada), not to mention the history of horror movie sequels, it's doubtful that this is the last of the Paranormal Activity we'll see.
In the first two Paranormal films, main character Katie (Katie Featherston, Chloe Csengery) and her sister Kristi (Sprague Grayden, Jessica Tyler Brown), were the possessed subjects. The third film brings these two characters together under the same roof as haunted children of the eighties. Daniel (played by Brian Boland), the step-father of the young sisters, is a trained videographer who has an obsession with home taping. Thus, the film maintains the home-movie-footage guise donned in previous films, however the plausibility of this device has lost all manner of ingenuity. Unfortunately, Daniel’s home movie antics spark an interest from the ghosts living in his home.
The girls’ mother Julie (Lauren Bittner) does little of anything productive (for the family or the film), save for dragging her heels and getting upset when Daniel brings up the possibility of spirits or gets Kristi talking about her (questionably) imaginary friend Toby. Ah, if only there were more to say about these characters...but there isn't. Sadly, all we are presented with is a diluted version of the couple we met in the two previous films.
One gets the feeling that once Paramount generated the bright idea to make a third installment in this dynasty, in order to maintain its low-budget feel they took an unused draft of the second film and repurposed it for the present shooting script. The most palpable difference between this and the other films, beyond the obvious age-of or absence-of children (depending on the film), is the nature of what lies beneath. However, the suggestions for why the characters are being haunted are so vague and obscure that connecting the tenuous supernatural dots about the film (or, God forbid, between the films) seems like a hideously thankless task.
Sadly, the film has difficulty even delivering the thrills and chills that it promises. The sudden, music-free surprises and camera tricks coupled with the fly-on-the-wall aesthetic intended to make them effective are so familiar at this point that it is an uphill struggle for them to achieve the potency they did in the past.
So, unless you're fourteen years old and going on a date (in which case this is the movie for you), perhaps just see if your roommate will drape a sheet over themselves and hide behind a door just when you least expect it. Or you can hold out to see if they can pull the rabbit out of the hat for Paranormal Activity 4 – the way it's going you'll only have to wait until next Halloween.