The movie wasn't that bad!
I saw this on HBO in the early 1980s, and thought the movie wasn't that bad. Mind you, it wasn't that good either. Being a fan of Hammer films, I was floored to find out Hammer studios put this out.
Years later, I found out one of the Carrerras' sons decided to up the budget on Hammer films, and this film was the first big budget Hammer film. Sadly, the son gambled the studio on this film, and the film bombed! It was this film that caused the collapse of Hammer not To the Devil a Daughter as some film scholars suggest. In a nutshell; the film wasn't that bad, but I would not have bet my studio on its success which is what the son did, and he lost the farm.