I think that my original guess- that this one would be one of the longer ones- is turning out to be completely wrong. I'm not quite an hour in, and I'm on 7-3. 
This is a pretty good game, though. I remember why it was so popular. Even with the older graphics, this is a wacky, enjoyable game, full of tricky jumps and a good theme song. The levels are pretty short, though. As I recall, the original only gave you two continues. I've used one so far. Still, I'm off to a solid start. I haven't played this game in ages, and I'm doing pretty well. I'm a little worried about the last castle, though. It's a maze, too, and I don't remember the right path. I really don't want to die when I get there, and have to fight back through all of world 8.