To be frank I completely disagree with the above critique. I found this film quite moving and very sad - I still can't stop thinking about.
I thought the way it was shot moved it along fairly nicely and was thankfully fairly anti- Hollywood which was a nice relief. Of course most Americans will probably not enjoy it because it's too subtle, nothing explodes and they actually have to think for a change rather than being told how to feel. If Hollywood had done this film it would have been all moody lighting, scary music and SFX - it would have been just another badly done version of The Exorcist (which I think is also a great film).
I think what I found the most interesting was that because this film was done in such an understated manner, you could actually understand what Michaella was going through in a much more realistic, believable manner.
There is a beautiful scene where near the end of the film Michaella's boyfriend takes her to her parents house because she is in such a bad state. She is soon surrounded by her parents and two priest all praying and chanting at her trying to exorcise her demons - her boyfriend steps away as he really doesn't know where to put himself or what to do as he watches the chanting - he looks like he is witnessing the dark ages of superstition; all completely anachronistic to the time he lives in.
Documentary style was a great choice - there were no true good or bad guys. And Michaella truly believed that she was possessed. So in a really strange way it was more an analysis of faith and belief. At the end of the day she, her family and the creepy priest all absolutely believed that she was possessed therefore she was.
Was that a good or bad thing, considering that nowadays most people barely believe anything at all?
Maybe she did fight an epic battle against demons for our souls like Saint Margarita - can anyone prove otherwise?