Am I Missing Something?

Too much about the plot just didn't add up, the writing was bad, some of the scenes were cringey and awkward,

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.

Exactly the movie you think it is, but not the movie you want it to be.