The Rifftrax version of this film has amused me through a dozen viewings. I just can't get tired of it. First of all, it's a well-preserved black-and-white, so it looks like Film Noir. (The stills I got off the web don't do it justice.) You can easily see the fine texture of people's hair, of wood, of fabric. In night scenes you get creepy shadows creeping over everything and, in the vicinity of Whitewood, MA, an abundance of fog. (There is no Whitewood in MA. Don't search for it.)
It starts out with a witch-burning. In general, New Englanders hanged their witches, but burning does make for more drama. Lucifer answers her appeal, manifesting as darkness and thunder--which doesn't seem right. After all, he's the light-bringer, and lightning is Yahweh's thing.
Patricia Jessel plays Elizabeth Selwyn, the witch who curses Whitewood and comes back from the dead to practice blood sacrifice. She enunciates her lines very carefully. Was this because of her stage acting or because she had to speak with an American accent? The Rifftrax crew pays no attention to Jessel's enunciation, but they do make fun of Tom Naylor's shifting accent.
Christopher Lee (behind Jessel) was the only big star. He plays a college professor moonlighting as a witch. In the tradition of the refined horror film, you don't actually see anything too gross or icky.
Anglican ritual, specifically in the Blessing of the Water section.
I think the Rifftrax crew have gotten so much funnier since MST3K. Their jokes aren't the obvious ones; they know how to surprise you.