Good watch, could watch again, and can recommend.
While I'm going to say that this movie was over-hyped quite a bit, it is good, but I don't feel like it really does anything specifically special.
It has a high level of good, but there is little I can see that would put that up to great. There are some scenes later in the movie as information is revealed that might surprise the audience, but I don't see it really as "scary" moments.
This is more of drip-fed information investigation movie with and all girls school, coming of age story, but the one thing it is clear it is trying to do, it tips its hand fairly early.
While I didn't find that detracting from the movie (it does add a bit of creepy atmosphere to the story), it could be a stronger reveal later.
Ultimately worth the watch, just go with low expectations.