Such a frustrating disappointment

I really wanted to like this movie. I feel terribly cynical trashing it, and that's why I'm giving it a middling 5. Actually, I'm giving it a 5 because there were some superb performances.

The acting in this movie is really good.

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.