There were many inconsistencies and quite a few flaws in both acting and dialogue. The swearing from the possessed was incredibly comical and the way one of the characters crawled up the walls simply made this film like a rip-off of The Exorcist. It seemed more like a horror film by Friedberg & Seltzer turned serious, along with the cinematography of the Blair Witch Project. Also, for a movie supposedly designed to be as if it actually happened - the script seemed very rehearsed especially at parts during exorcism scenes.
The ending was probably the worst part, you could see what the director was trying to achieve: confusion in the audience as to what will happen next, a seriously poor cliffhanger. In todays society, you can't simply just finish movies like that, it was uneventful (like most of the film). If they are making a sequel, I most certainly will not be seeing it.
Yet despite my overall dislike of the film, I didn't walk out. I suppose I didn't want to feel like I wasted money on a ticket.