How bad is it? It's pretty damn bad.
Should you see it? It's on a Something Weird double bill with "Monster A Go-Go," so if you're okay with that, then watch it. Otherwise, no.
This gets mentioned on occasion as the worst film ever made. It was shot silent with a narration track added later (like so many of the worst films on this blog - see Beast of Yucca Flats, for example). A woman has a seance - or at least meditates with a couple of candles - and brings up the title witch, which forces her into ever worse sexual encounters. Nothing's shown (there are a few breasts), but the film shows faces during what's supposed to be rape, necrophilia, bestiality with a snake and so on, usually in masks and distorted with psychedelic lighting and effects. Finally, the girl's brother is turned into a sex vampire, which is not adequately explained. The score has a lot of classical music, but also steals (I think) a Pink Floyd song and plays the film's theme song 8 to 10 times. There are some swear words edited out, but that seems to be the only editing in about 80 minutes.