Ugg the bad writing
Due to the strong acting I enjoyed this movie enough as a formulaic horror movie.
But if you think about it at all, the bad writing is hard to ignore.
There were so many elements that screamed out as being present only as a feeble explanation for some other thing. It's like a lazy committee sat around and came up with quick fixes for problems.
Why is one daughter an fervent animal lover? Oh so we can say she has a pure spirit.
Why do the parents live apart? Oh, so we can have some tension of wondering if the child's behavior is because of parental abuse, or effects of a divorce.
But why would the mother divorce a patient, loving and considerate father? Let's say he's too involved at work.
But we don't want him to be that bad of a guy, since we already included that pure of spirit nonsense from before. OK, let's say that he's a devoted sports coach that comes home late from practice. Great, that will give a reason for him to be divorced, but also still keeping his spirit pure!
How can we justify getting rid of the boyfriend who is by all evidence decent and caring? Have him say something mildly harsh to a demon child ("You're just going to have to get used to it.")
How can we show that both parents are making compromises to reunite and that it's not just the wife coming to her senses? Let's pretend the father takes a pass on a big job offer to stay with his family.
Why is the rabbi exorcist a young guy that listens to cool music on his ipod? Because we signed Matisyahu.
How can we kill off the rabbi? Have hero dad inexplicably give him a car.
Why don't they just start by commanding the demon out, why have all the candles and trivial stuff first? Oh, so we can include a water effect and bump up the running time.
Why does the demon jump over to the dad? Oh so we can include a predictable "surprise" when we think everyone's safe and he gets the devil eyes.
I really don't have a problem with formulaic devil movies, but I would appreciate a bit more respect for the viewer. Have some element where the viewer can put things together for themselves and feel smarter for worrying about the risk.
For example, suppose the ring actually had some purpose, like it was required for the demon to enter and leave the body.
The audience could be tense if they know this, and watch the girl play with the ring a couple times but never wear it, then lose their minds when she finally puts it on. Then the ring could later be lost, and the audience will realize long before the characters do that the demon can't be removed until that ring is found. Not that any of this ring story element is necessarily great, as I just came up with it in two seconds. But it's an example of how you can build tension by having the audience know something and feel clever when they predict or fear things based on that knowledge. Instead, the ring in the movie had exactly zero meaning or purpose. And that same theme could be said of the whole movie.