I actually saw this movie as a child of about 10, and I loved how absolutely scary it was. I must say, that I wouldn't recommend that very young viewers are allowed to see it, as it could terrify and leave lasting fears in them.
This is a very dark, very desperate movie, not to be missed. The acting is extremely accomplished, especially considering the ages of most of the cast.
Lighting is used extremely effectively, making the viewer wonder what is coming next, or perhaps what might be being missed that might be essential.
This movie still sticks in my mind 36 years later as one of the most effective dramas I've seen.