Ugh, not happy. It felt like The Last Exorcism was constructed entirely of minor plot twists that really weren't exciting. The whole thing was rather slow and uneventful. I'm a sucker for found footage films, and I don't understand the decision to utilize that style while incorporating some music/sound effects. I wish I listened to the other reviews.
It was corny at times, and I felt it was a little slow, maybe lacking any real thrill sometimes. But, the acting was largely fantastic and I didn't see many wholes in the story. That ending, though...that was really terrible. It just simply ended. I get it, the prophecy was fulfilled. But, as a viewer watching a horror film, I wasn't impressed, or even satisfied.
Without Ashley Bell this is a standard genre film with as conventional structure and expected ending as many forgettable horror films. This still is a standard genre film with as conventional structure and expected ending as many forgettable horror films, but Ashley Bell is fucking terrifying. I would personally edit out the entire film except her.