I loved this movie. It's sort of a marriage of Octoman and Swamp Thing. I expected the story to go in one direction that was never really explored too deeply, but that's besides the point.
The Muckman looked great and some of the characters were pretty solid, while others were 2 dimensional throw aways, but doesn't that just add to the Drive-in movie sci-fi charm? There was some fantastic miniature work in the movie. A real pleasure to see in today's "do it with computers" world.
The movie isn't scary, but it is fun. In a campy, goofy, watch it with friends and laugh about it later way.