Sonika Edwards (Suzq22)

It was a psychological thrill ride, with the scares and suspense brought on by what was "unseen" - and believe me when I say, there were some "unseen" scenes that could give you the creeps if you're easily creeped out We did hear some audible gasps and jumps of fright from the audience around us.
The shaky camera style also induced a bit of headache and nausea, and the film style made it feel all the more real.

I compared it to: the Exorcist meets Blair Witch.