I get why people are frustrated with this movie. As well-made and atmospheric as it is (the lighting, colour palette & VFX deserve special praise), absolutely none of it makes any sense until you know the twist ending. After that it's actually quite good, but it takes so long to draw you in with anything that actually has a point - and even then I can see why some might feel it isn't worth it, as the premise of the twist is a little shaky. The "horror" is mildly chilling at best, not scary, but overall this isn't a terrible film; it's just not as good as it might have been. Which is the most frustrating thing.