So adjust your expectations accordingly: The Witch is atmospheric, well-made, and creepy as hell. But it's not the sort of movie that'll have you covering your eyes or jumping out of your seats (and that's OK).
The Witch follows a family living in 1630 New England who have recently immigrated from England. After being banished from their town for a religious disagreement, the family's father decides they'll strike out on their own and settle in the wilderness. If God's on your side, what can go wrong? Shortly after they settle down and build a place for themselves in a remote area, the youngest-born child goes missing and other strange phenomena begin to imply that an unsettling black magic is at work nearby.
There are a few things The Witch does really well that's set it apart from other releases in its genre. The cast is great (including several Game of Thrones faces), particularly the super-eerie twins. The music and sound effects pair with the desolate and stark cinematography to slowly and carefully build up an atmosphere of dread. With one exception, what isn't shown tends to lend to the horror of the film, with careful attention paid to what's left in the shadows and what's revealed on screen.
Some people will have problems watching The Witch for two reasons: It's slow (I've seen comparisons to Malick), and it's hard to understand the dialogue. The film makes an admirable commitment to get the language and dialogue as accurate to the time period as it can, which certainly lends a great deal of authenticity to the atmosphere. But in the first 15 minutes in particular, there were parts of dialogue that I completely missed or failed to understand due to a combination of a really deep, thick accent and the unusual language. I'm actually still not certain why they were banished from their home.
My biggest personal complaint with the movie, though, its the film's last shot. The Witch shows so much restraint in almost every place it counts, but the over the top ending left me feeling like the movie had suddenly betrayed its objective.
In all, The Witch is worthy of its praise, but it's also certainly a film that critics will love, horror fans will latch onto with incredibly high expectations, and a certain amount of letdown will eventually occur. Director and writer Robert Eggers couldn't have asked for a better vehicle for his debut, though.