I see other reviewers are upset that the film started off with a lot of build up for a mystery we hoped would completely unravel, and I understand some are upset it didn't answer a lot. But I challenge anyone to revisit the film and declare they didn't completely immerse themselves in loving the experience. It was a load of fun, great staging, acting, and definitely music did its fake share of chores.
Polanski is good with the whole Satanic thing, he seems to know a lot about it. This round operates differently from Rosemary's Baby, more of a detective story whereas Rosemary is an exercise in terror, but the unfolding and understanding of Satanic cult is similar. Orgy, rituals, power seeking, and of course death.