I'm a fan of psychological thrillers. I don't like gore, slasher, or jump scares, they feel cheap. I am stipulating this simply because most of the reviews seem to give the impression that the only reason why you wouldn't like this movie is because you are looking for one of those aforementioned qualities.
I didn't like this movie because it was slow, there was zero character development, and it wasn't believable.
For a movie to feel connected to it, it needs to have strong character development. I need to care about these people. In this movie, I just didn't. They felt like actors in a movie, they didn't feel like actual people. It also needs to have some kernel of believability. Obviously it's not real, but there needs to be some small amount of "ok, here's the situation, here's how people in this situation would act." That is missing from this movie because nothing horrific is actually happening. Most of the movie seems like unfortunate events, and maybe some psychosis.
The pacing is so, so slow. There is a way that this can be done properly to hold interest. This movie did not meet that bar. This also removed believability for me. Families don't move that slowly. They are not this dramatic in everything they do. Everything was met with long periods of silence.
Don't even get me started on Peter's "crying".
This movie gets 2 stars from me because there was one scene at the end that I did find particularly disturbing, and even has me a little spoked as I write this. Aside from that, I would not call it a horror movie, and certainly not a thriller (as there was nothing thrilling about it), and as a drama, it was an incredibly boring one.