If I were you I certainly would buy the game. Although the game is short, it is really fun and you can use abilities from the first game and new abilities that can only be used with the card system. But honestly playing it on the GBA is kind boring, if you can buy KH II FM+ and you will gain KH re:CoM with even more abilities, the coolest scenes of the three games thus far, harder than the original and what is better even if you don't understand Japanese the game will show what is needed to use the abilities and don't worry you will find all the scenes subbed at youtube. So in my opinion buy KHII FM+ even if you won't use KHII FM+ at least you will have the best KH CoM.