To start with, the first half of this film is very slow. You will wonder what is happening, and what is the point of all of this. In fact, it is truly like watching someone's home videos from 1995 -- very amateur, very boring.
Yet, this is what makes this film succeed in the end. These are truly human characters without any of the Hollywood tricks. They are real; either you sympathize with them, or you don't. End of story. If you don't, you give this movie a one-star review and go on about your business. But if you do, the suspense will grow on you gradually, creep up on you from behind, until you find yourself checking the windows and doors to make sure they are locked.
When it comes to this kind of movie, I am no easy customer. Only Carpenter's _Halloween_ and Kubrick's _The_Shining_ have affected me. _The_Blair_Witch_Project_ (the iconic found-footage film) scared me the first time, but by the second viewing, I was hoping for the annoyingly contrived characters to be killed. Even after several viewings, _Atrocious_ has retained its intended effect. It is a well-crafted thriller that may seem tame by today's standards, but which creates an authentic atmosphere of horror and suspense unparalleled by few movies released in the past few years.
Is it perfect? No. Even though it achieves its intended effect, it really needs something to draw the attention of its audience much earlier in the film. I suspect most negative reviews are written by reviewers who only saw the first half. Do yourself a favor and watch the entire film, then let's hear what you think. You just might be pleasantly (unpleasantly?) surprised!