Incredibly lazy level design and clunky movement mechanics.
Many levels are designed for only 1 player, like most of the minecart ones and rocket ones. I was playing with my brother, and there was literally nothing for him to do.
The auto scroller levels are some of the worst levels I have ever played in any video game ever. I have no idea how this game has such a high rating. I would guess it's from nostalgia and only nostalgia. I used to play this game as a kid, and I loved it. Sadly it does not hold up at all.