What makes it different from others?

I am only giving this movie a 1 for the great cast, though I can't imagine what any of them were thinking. This movie was horrible

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.

After playing with our expectations, this turns out to be a very different sort of film.