The Devil Inside was released on Jan. 6th, 2012 in the US. It's a possession horror movie written by Matt Peterman and William Brent Bell, and directed by William Brent Bell. The duo's only prior collaboration was 2006's "Stay Alive", which is a bit of a guilty pleasure movie. It, like many other horror movies, failed because it didn't quite figure out how to integrate technology into a horror story. Horror as a genre hasn't quite figured this out, so I don't really blame this on them. I just bring it up to lend some context to saying I think Stay Alive had interesting visuals and concept but was pants-on-head retarded. It's very into the bro-horror idea that horror is sometimes funny because it's bad. With that, I find it very impressive that The Devil Inside is very much the opposite sort of movie.
The Devil Inside generally plays itself as a straight faux-documentary, using a seasoned professional cameraman as an excuse for multiple cameras. You can see them discussing setting up the cameras, and also they do interviews with various people they're following around. The director also records himself, which seemed a bit odd in the context and I could've done without those bits.
The basic premise here is that 20 years after her mother went insane and killed several members of her church congregation during a botched exorcism, Isabella Rossi travels to Rome with a documentary film maker to reconnect with her mother and attempt to understand her condition. We go with Isabella to an exorcism theory class at the Vatican, to a mental hospital run by the church, and to the apartment of 2 young priests Isabella befriends after the exorcism class. The class and the interviews with the 2 priests, Ben and David, are used to explain the rules of the movie's possession mythology.
Ben and David have actually gone rogue and are performing exorcisms on victims the church officially won't authorize an exorcism for, arguing that the rules make it impossible to prove possession without attempting an exorcism but preclude an exorcism without proof. We go with them to see an actual exorcism in progress on Rosalita, where they explain how they use medical science to track the symptoms of possession and progress of the exorcism. I thought that bit was very interesting, and I don't think I've seen a single other exorcism movie where the religious figures attempt to integrate and benefit from science. This is also probably one of the best scenes in the whole movie. They made a real smart decision to cast either a gymnast or contortionist in the role, and the positions her body contorts into are just unnatural. This is aided primarily by some pretty good practical effects, and one very short shot of CGI. There is another scene later where they attempt an exorcism on Isabella's mother that is also very good and tense but not as visually uncomfortable as Rosalita's exorcism.
After the unauthorized exorcism attempt on the mother the characters go into panic mode for a bit and begin to show signs of stress and uncharacteristic behavior. Even though the pace was good I didn't like this bit because it seemed like the movie had gone off the rails. Towards the end of the sequence the story's protagonist shifted from Isabella to Ben, but the documentary framing device remained on Isabella. I like that in principle, since they didn't compromise the character motivations for simplicity's sake. However, they never explained why they decided to do that.
I've previously expressed my annoyance at movies that try to be mysterious or edgy by not neatly tying up their plot threads at the end but actually just end up deliberately introducing something in the middle of the movie and never explaining why it's important. This movie is guilty of that to a minor degree, but it may be a casualty of the abrupt way they chose to end the movie which they may have done in hopes it would drive traffic to a website they advertise before the credits which probably extends the story. I haven't checked the site so I'm not sure if it was successful at all.
All in all the movie isn't nearly as bad as people seem to be saying it is. It does a lot of things right and delivers a pretty interesting story. It doesn't get so caught up in trying to be realistic and character based to be visually creepy. The ending was a bit of a disappointment, but I thought it was really entertaining. Nowhere near as good as Exorcism of Emily Rose, but way better than The Last Exorcism.