I will say this movie rubbed me the wrong way - it wanted to be sooo clever, but it really wasn't. The premise nor the writing really impressed me.

I definitely found myself bored a few times, but there was about 15 minutes where I was really into it (the elevator scene, of course).

Wasn't scary, wasn't funny... it just kind of was. I remember thinking I wish I was watching a straight-up horror movie instead.