Lack of good storyline.

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.

I enjoyed watching this film and would recommend other to give it a try , (as I am) but this movie, although enjoyable to watch due to the better than average acting fails to add anything new to its storyline that is all too familiar to these types of movies.