This is Mamá, a short film that impressed prolific director Guillermo del Toro so much, he became very willing to produce a feature film.
Andres Muschietti is also the director of the full-length version, and I've no idea how faithful it will be to his three-minute short. Frankly, I'm not a huge fan. Yes, some parts (especially the beginning, when you have no idea what's going on) crept me out, and though the scenes look like they were shot in a couple of long takes (which I like), the screams of the children diminishes the scare factor a bit, and such goes on until the ending, a tad cheesy one, if you ask me.
I'd still see the full-length movie, though, because it has Jessica Chastain and because I'm curious to see how Muschietti would transfer the material to the big screen.
Of course, you are your own judge. Watch the short film below and tell me in the comments section if you find it scary or not.