It was George Reeves' first go at playing Superman, and he did it well. Superman is a deadly serious and no-nonsense kind of guy in this. Not afraid to put people in their place by taking their guns, or giving the undeserving townsfolk an acidic comment.
What I really enjoyed was the idea that the humans are the bad guys. The Mole Men wander around doing no harm, but people decide to hunt them down out of fear.
Right from the get go, Superman is on the side of the little guys, defending them against the unreasoning humans. With all the talk of fear making people act irrationally, coming as it does in the early days of the McCarthy era, it was quite an adult direction for the flick.
As films go, it's a bit slow but mercifully short at just under 60 minutes. The production values are low, and the Mole Men are cheap. But I rather like Superman's characterisation, and the take on the base idea.
Quite reasonable for a piece of fifties sci-fi.