Definitely something to own in case you want the pieces of a fractured story to connect!
The card system may seem complex to use and hard to understand at times, but I was more interested in the plot of this game. Wanting to know how this connects to the 1st and 2nd game makes complete sense to me. It basically, sets the stage for what's to expect in the 2nd game! What can you expect from the great Tetsuya Nomura? I assumed he created this game to make every storyline become resolved and make sense.
Overall, this makes the Game Boy Advanced version look obsolete. No disappointment! I loved every minute of it and I intend to keep this in my "Kingdom Hearts" collection!