Horror fans should definetly give this movie a watch.
You know when you used to shine a torch up your face to look scary as a kid? Times that by 10 and add claustrophobic sounds and nauseating camera work. Thats the feel. The movie follows a crazy guy called Dave. Michael Parle is really great as Dave. The dialogue feel like it was loose and left up to the actors at times, which was fine.
The only downside is that if you're not invested in the characters or don't like the way the movie looks you'll probably get a bored. There is a short part when Dave isn't around and he is missed, as you're left just watching Pete with torch in a crazy environment. Ends with a kind of freak show. Not the most original development.

It was like being trapped in a nightmare. Does it make sense? Not really. Got weird at the end?

Don't answer the door to strangers.