This was, a competent modern day slasher. It doesn't innovate, but it takes aspects from slasher history, and piles them in to a competent, fun, bloody package.
It pisses me off to no end to see that some people thing that "Saw' invented the "Whodunit" aspect of horror films. Not only did saw NOT invent that aspect of films, but it's not emphasized in this film. It's an aspect of the film, yes, but it doesn't rely on it as a driving device.
This is a film for people who miss the slasher film, and are tired of "Saw" and it's imitators.