Yeah, the smartest thing would be to rent it first. I love the game, its great, one of the best GBA games I have played. The card system wasn't as bad as many people said, but it wasn't great either. I say rent it, but it is worth buying I guarentee. It's great. It wouldnt be nesessary to play for KH2, but it would help, as Nomura stated. So I suggest buying it for a little back up on KH2.