Probably nothing. I played it as a child and loved it.
But I would have to say; I was in Prep and people who were in grade 6 were showing me this game called 'Pokemon', they jumped of a ledge in the game and told me you press the middle of the D-pad. So, me being naive and all (Hey, I was like 5) I went out and got the game for my birthday only to find out that you couldn't jump. That annoyed me the most. xD
Oh! Or the fact I was a very poor reader and had a hard time beating the game.