Ruined by the last 30 seconds of the movie...
This was a great horror movie until the last few lines at the end - 'You are Paimon, one of the eight kings of hell'. They should've just left it to the audience to figure out instead of that goofy dialogue.
It's amazing how a few lines of dialogue can bring a movie down a couple notches. It's like imagine if Bruce Willis in The Sixth Sense verbally expressed that he realized he was dead at the end, it would've destroyed the execution of the twist.