It may be difficult to watch, a bit much on the senses BUT it's worth it. I wasn't expecting an engaging horror/thriller that keeps you wondering right up until the end...AND to be thought provoking/educational.
Don't read any other reviews if you don't know much about the film as there are spoilers.
I don't remember the last time I reviewed a film but this one was worth the time it took.
Basically...watch it, watch it and most definitely watch it.