Katie (Katie Featherston) and Micah (Micah Sloat) are a well-to-do, young couple living together in San Diego. They are "engaged to be engaged," and Katie's a university student while Micah is a day-trader who presumably works out of his home. Katie and Micah have begun to hear around their home unexplained noises at night, and Katie tells a psychic (Mark Fredrichs) that she has had encounters with the supernatural all of her life. The psychic tells the young couple that what is occurring is probably not a ghost and what is inside their home is not a haunting. Something paranormal is attached to Katie and it is fixated upon her. Micah buys a bunch of wonderful techie toys, like an EVP meter and an HD video camera. His intention is to film the odd goings on within their home and with his investigation help Katie. The viewer gets to see the results of Micah's experiment through solely his footage in Oren Peli's Paranormal Activity (2007). 
Paranormal Activity was a huge box-office success in 2009 and it eerily mirrored the success of another popular and similar film a decade before, Daniel Myrick and Eduardo Sánchez's The Blair Witch Project (1999). Both films benefited from a massive, word-of-mouth, grassroots campaign, as everyone who had seen the film said it was very scary. Both are low-budget films made with unknown actors with debut filmmakers behind their genesis. The biggest similarity and each film's primary appeal is its shooting style: a film composed completely of footage shot by its on-screen participants. The "found footage" film has a very noticeable inherent flaw for traditional film viewers. Not only do the film's participants have to chronicle the film's action with their cameras, they have to drive the film's narrative as characters. Hence, the viewer is often left wondering if the character is acting "in character" by filming the on-screen action; or is the character filming the on-screen action for the benefit of a viewing audience? The best example of a recent film which matched character motivation and character camera-chronicling is Jaume Balagueró and Paco Plaza's [Rec] (2007) . When the character motivation and the character filming do not jibe, it immediately takes the traditional viewer out of the dramatic action displayed within the film. Paranormal Activity suffers from this flaw with its character Micah, but as I've noted, it's an inherent flaw of the shooting style. Subsequent film makers, I'm certain, are going to conquer this filming (and narrative) style and produce more seamless films. Nonetheless, this inherent flaw in Paranormal Activity is almost completely overshadowed by its extremely effective paranormal scenes and scares.
I do not believe in ghosts and the like, as does not the overwhelming majority of today's culture. Most folks have a fear of being kidnapped, beaten, degraded, violated, having their fingers cut off, and killed (hence the popularity of the torture/kidnapping horror film). It's a primal fear, but Peli with Paranormal Activity is able to tap into another one: the almost complete vulnerability of one while sleeping. Unless you're a fan of crystal meth (and you're seeing ghosts, ninjas, and C.I.A. operatives all around you), everyone has to sleep; and Paranormal Activity's best scare scenes occur while Katie and Michah sleep soundly in their bed, as the camera focuses upon their bedroom and peeks out through the door, giving a glimpse of the rest of the house. Wisely, Peli has Micah's camera equipped with an on-screen digital clock in the right-hand bottom corner of the screen. He's able to use this innocuous device, especially in a couple of scenes where he speeds up the video, to clever effect. Likewise when Katie and Micah go to bed in the evening, the night is marked by an on-screen title card with a documentarian-type numbering and date of the happening. These title cards are used to excellent theatrical effect, as if it foreshadows something momentous about to happen (and most of Katie and Micah's nights are rarely free from activity). Peli's use of audio is also tops, including an extremely judicious use of lights and, especially, shadows. With little foreshadowing, nearly every evening contains unexpected paranormal events.
Peli attempts to shade over the inherent flaw in Paranormal Activity's shooting style by portraying Micah as an insensitive boyfriend. As the ladies are well aware, all of us boyfriends suffer from selective hearing, selfishness, and a degree of insensitivity in our relationships. During the first two-thirds of the film, the viewer can assume that Micah really doesn't believe in Katie's supernatural dilemma and that Micah is having a bit of fun, with his filming and technological toys, at Katie's expense. During the final third of the film, when the events in the house have really taken a toll on Katie, Micah does attempt to be sweet, caring, and sensitive; but when Peli has Micah embrace Katie or comfort her while she's crying, the intimacy of the scene is undercut by the fact that Micah's still filming. Katie's super sweet and really tolerant of Micah's behavior, despite the escalating series of events in the film. There are other scenes within the final act that standout more as a chronicle for a viewing audience rather than two actors portraying characters. This is also a minor quibble, but Micah and Katie's home is abnormally clean and sanitary. So clean, that the entire house seemed to shine in the light. I was waiting at some point for the (at least) twelve-to-fifteen person cleaning crew to come in one morning while they were having breakfast and work the house over. 
Featherston and Sloat, as Katie and Micah, respectively, are good in their roles. They seem like a credible couple and are, for the most part, seemingly normal people. Fredrichs's psychic character is written well by Peli: he comes off as a down-to-earth, approachable character, instead of a traditional, stereotypical, eccentric and kooky type from past films. His performance is very good, as well. I don't watch very much recent American horror these days, but I have to say that I very much enjoyed Paranormal Activity and think that it's one of the better horror films that I've seen in a long time.
