I watch a lot of horror movies (and I do mean a lot of horror movies--they're one of my passions), so when I say that this is one of the finest horror films I've seen in recent years, you know that's not empty praise. And in fact this really is one of the finest horror movies I've seen in recent years. It's wonderfully performed, beautifully shot, and amazingly suspenseful throughout.
Admittedly, it's a long movie and a bit of a slow burn at times, but none of the slower sequences are ever boring. Rather, they're fascinating as the filmmakers gradually reveal information and provide layer after layer of suspense. And this is genuine suspense. The viewer is never entirely sure what's actually going on. This is, in large part, a tale of suspicion and paranoia and the viewer consistently struggles to know which suspicions are founded and which really are just the products of paranoia. It's not a new cinematic device, but it's used about as well as I've ever seen a movie use it. Similarly, the basic plot and premise of the film will be familiar to horror and thriller fans, but they're rendered perfectly to create that rarest of all entities: a horror movie capable of haunting even the most jaded of horror fans.
If you haven't seen this yet, you really owe it to yourself to watch it.