Saw it last night. It's absolutely the real deal. Extremely unnerving and frightening on a very deep and almost personal level. It got to me in a way no film has in many years, it gave me chills and made me feel genuinely unsafe on several occasions. Masterful use of building dread and tension. The atmosphere is bonkers, and it's getting compared to The Exorcist a lot, but it reminded me a lot of The Shining more than anything.
Best horror film to come out in a long long time. And the fact that it's the director's first feature film is mind blowing. He feels like a master of his craft who has been doing this for decades. Anyone with even a passing interest in horror should see it asap.