How bad is it? It's a typical giant reptile movie, so it's not very good.
Should you see it? Yes. Skip the remake, though.
The film relies on back-projection and live monsters moving around scaled-down toy sets. It also relies upon stereotypes and pointless conversations. I've always thought the coolest thing about gila monsters is that they defend themselves by squirting blood out of their eyes - that would've been a cool addition to this film.