It's entirely possible that sending the audience out feeling lousy was intentional

I wanted to like it more than I actually did... But much of the humor totally escaped me and I walked out only mildly impressed.

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.

The film never slows down or bores, plunging from one harrowing sequence to the next.