I just watched it, I really enjoyed it.
Did anyone notice the drawing behind the father on the blackboard when he was sitting in the classroom... SAW reference maybe?
I also noticed how the dialogue of the whole movie was presented in lower volume than most movies, so you had to turn up the volume which set you up for some crazy intense dynamic scenes where the audio made you jump along with disturbing visuals.
If you have a system capable of quality reference level sound (especially in the LFE region) and maybe even some bass shakers, this movie is a good one to have some fun with.