It's not great, but it is good. I like the motive of holding onto a metal monopoly (even if the scale makes little sense and tools can be made from other materials—this is, after all, still Doctor Who). I also enjoy the way it's set up to be a typical creature feature with a looming people-eating monster, and then turns the assumptions necessary for that upside down. Despite its...unfortunate design, the creature is otherwise a very interesting concept.

Also amusing is the way every single character thinks that they're the main character of this story, and most of them are wrong. The bandits in particular spend the entire story running around trying to make themselves relevant, but they never are. Romana and the Doctor (and K-9) are great as always.