Apart from Paul Ehlers giving a nicely intimidating turn as the killer, the cast isn't much to write home about with Gaylen Ross from Dawn of the Dead as the Final Girl being the main standout, and even then she doesn't really do a lot. The most interesting thing about her in this film is that she works under a different name, probably due to the film being a non-union production. Everybody else is pretty dreadful.
What the film does have in its favor is a decent sense of energy and the killer. Madman Marz is an impressively gruesome, formidable slasher villain with inhuman strength and apparent invincibility. He sort of reminds me a little of the killer from the Hatchet films, Victor Crowley. Both are relentless and rack up a pretty respectable body count. And by respectable, I mean it gets to double digits. Sure it's only ten here, but all ten are, for the most part, pretty damned impressive with two decapitations: one by axe and the other with the hood of a car, a gory impaling and some other nasty bits.
I also like the general setting and atmosphere as the entire film takes place at night in a small section of the forest where the camp is. No stuff in the nearby town, no police presence, the guy in charge of the camp heads into town twenty minutes in and isn't seen until the last minute. It gives the film a nice claustrophobic feel that most slasher films lack.
Madman is a solid meat and potatoes slasher movie that doesn't try to be much more than what it is. The killer is cool, there are some neat deaths and there is a nice aura of ruthlessness in the way the film casually offs pretty much the entire cast including the Final Girl. It's brutal but not in a mean-spirited way. You can do a hell of a lot worse than this one if you're looking for a cheesy 80's slasher movie.