Good concept, poorly executed.

Excellent, Without a doubt!!

It's funny, it's tense, it features two great performances from two actors and the director expertly creates a web of odd tension where you actually don't know what is happening for the majority of the run time.

There are moments in this movie where the great movie it could've been peek out... They're fleeting, here, but they're worth savoring, and they happen often enough to make it worth your while.