Hereditary is not a horror. It's just a 2:7 min long uncomfortable drama.

Apart from the fact that the acting is great it didn't workout for me at all.
We have been getting lots of unconventional horror films from past few years like It Follows, Get Out, It Comes At Night, Babadook, A Quiet Place which have helped redefine this genre as horror but there is nothing about Hereditary which is close enough to qualify as a horror because it fall flat on everything it tries to do. The character arcs don't make sense, the origin of the cult god felt like a prank. The ending is a prime example of lazy writing. In the end the overall 2-3 scares is all I got from it.
Watch it for the great performances by the actors and the first half.