Once upon a time there was a news crew investigating an apartment with some firefighters after a desperate 911 call. A simple story turned into a screeching, howling nightmare in a blink of an eye. How many variations of this are we going to get?
Good acting. Nothing special.
The film quality was just OK. The lighting was too dark to see what was actually occurring in about 35% of the film but what was shown was pretty good. The jump scenes scare to you, the graphic nature of the movie shocks you, and the suspense, well, suspends you. A solid horror flick.
The violence is, indeed, monstrous. Throats are bitten and ripped, fractured bones penetrate flesh, etc.
Supernatural and plausible a the same time. Difficult to assess.