How bad is it? It's mediocre twaddle.
Should you see it? No.
I couldn't imagine why this was considered by some to be so-bad-it's-good, but it turns out to be another film lampooned by MST3K that wasn't really anything on its own. It's not even the worst ship voyage based animation; that would be "The Legend of the Titanic," where everyone miraculously survives.
Christopher Columbus discovers America with the aid of a worm who has his own plan to save a fairy princess. The characters are poorly drawn - as is the animation - and the plot devolves into a shouting match between an evil lord named Swarm and a suddenly gold-obsessed Columbus. It doesn't make any sense, the music doesn't help, the voice characterizations of Dom DeLuise and Corey Feldman are questionable at best and there seems to be some cultural issues between the German crew that made the film and the source material.