OK, guys. Hereditary has completely rocked my world. I got the same feeling watching this as I did back in '99 with The Sixth Sense. And, no, it didn't have an "ahha, gotcha" moment like that. Instead, as more and more layers are peeled back, and scenes just... happen... they fundamentally alter what you have seen before. This is a movie I want to watch again. And again.
Before I go further, I must say that this isn't for everyone. The first 90 minutes is amazingly slow. If you want a "horror" movie to jump scare the shit out of you, then this isn't for you. Even if you prefer the movies that buck the PG-13 trend of cutaway blood splatters to give you shocking moments (think The Conjuring), this isn't for you. It's because this movie isn't truly a Horror film. Much like Sixth Sense wasn't horror. This is a psychological drama that builds to a 20 minute sequence that scared the absolute hell out of me far more than any James Wan joint ever has.
I'm going to add spoiler tags here, because I'm going to get into some really deep shit.
It has been a LONG time since I've left a theater with chills running down my spine. Modern horror doesn't bother me. This isn't a new "The Exorcist" or anything like that, it just has the potential to be. That last 20 minutes felt like being caught up in a flowing river rapid, unable to control anything. If you like dramas and horror, then you will LOVE this.