Rated Oddity 9/10
A couple of scenes in this gave me the most visceral fear response I've had to any film ever. I don't think I've ever turned on the lights mid-film before, either. The worst (best?) part is there's a few places where you know exactly what's going to happen, and yet it's still somehow terrifying in the moment.
It's not just jump scares: it does a good job of building the tension up, and the plot was a lot cleverer and more interesting than I expected. Carolyn Bracken pulls double duty as the twin sisters, and does a bang-up job portraying them both.
It's nearly a 10/10 for me, but the ending felt like a bit of a letdown. Almost like the film itself was being a bit smug at ending where it did. On top of that there was a bit too much foreshadowing for some bits, which is especially strange given how well most of the plot guards its surprises.
Definitely a good choice of film to watch on Halloween though. Now if you'll excuse me I need to arm myself and do a sweep of the house just to reassure myself.