The original highlander was one of those "So bad it's good" movies. I mean... they had a Scottish actor (Sean Connery) playing a Spaniard (he can't sound anything but Scottish) and Christopher Lambert (who also cannot change his voice or accent) playing the Highlander. The dialogue was terrible, the story was passable, one of the cops was an expert in metallurgy (seriously wtf?) but it's still entertaining. The best thing about the movie was the soundtrack by Queen, and also the Rifftrax. If you've never seen the Highlander Rifftrax go do it.
The TV series wasn't based off of Connor but one of the other MacLeods... Duncan, and it wasn't terrible. It's watchable just like the first movie.