How bad is it? It's not good.
Should you see it? John Ashley fans will want to take a look; others won't care.
If not for Jess Franco, Eddie Romero would be remembered as the worst director from the Philippines. He did a number of films with John Ashley (who was in the Beach Party film series) as star. In this one, rather than the hero, Ashley plays the villain, a guy who makes a deal with the devil which allows him to absorb the evil of those he kills and turns him into a variety of beats, including a scaly werewolf-like one. The make-up is poor, especially the gore, and the budget is quite low, even with Roger Corman as executive producer.