I've seen this film described as horrifying, realistic, compulsive viewing, and so on.
I found parts in the first hour a bit interesting & scarily jumpy, and the build up was so good, but it descended into a clichรฉd weird witches coven/ demonic possession story and let me very unsatisfied by the ending.
Toni Collette was as ever great to watch and portrayed Annie so well, but it was a waste of her talents as it ended up reminding me of an early hammy hammer horror film.