First off, yes, the movie did serve as the inspiration for the name of the band.
There are actually two versions of this movie, the Italian version and the American version. Some studio suit decided to “Americanize” the original to make it more “consumer-friendly” to American audiences. As to whether or not these alterations helped or weakened the film, or made no discernible impact either way, will be for the viewer to decide. I’ve only ever seen the American version, so that is the one upon which I will comment.
BLACK SABBATH is pure giallo, even in its American form. Pure Mario Bava. With Boris Karloff serving as “host,” it tells three different stories. “The Telephone,” a revenge narrative starring the gorgeous Michèle Mercier, who is menaced by an old enemy who may or may not be a ghost, is the weakest of the three. “The Drop of Water” is also a revenge story featuring a ghost with a grudge, but it’s more straightforward. There’s no question as to what’s going on. “The Wurdalak” is unquestionably the highlight of the film. It features Boris Karloff as a vampire, and is notable in that it follows the trope of medieval vampire predation from folklore and historic accounts. With vivid colors and impressive sets, BLACK SABBATH ought to be on every vampire mark’s must-see list.