How bad is it? It's a very dopey kid's film.
Should you see it? Yes. It's a very charming dopey kid's film.
Every nation seems to have it's own turkey of a film for Christmas and this one's French-Canadian. A martian helps children find their way home and then they return the favor. The spaceship and in particular, the martian himself, is bottom-of-the-barrel, using whatever props must've been at hand. The martian entertains the children with magical powers (involving shutting the camera off and moving) and a ton of candy. It's loopy. Not as good as "Christmas on Mars," it's way better than "Santa Claus Conquers the Martians."