The fact that this wasn't originally a Mario game is very conspicuous; Super Mario Bros. 2 is totally bizarre, and playing it often feels like a strange fever dream (which, y'know, appropriate). I think this actually makes SMB2 more interesting to play than SMB, and the tighter controls make it a bit more fun too.

The original NES release has a pretty awful lives system, and the game is hard enough that were I not playing with the aid of save states I'd have likely quit out of frustration.