I've completed each one.

For those who do not know what they are, they are the same version of the game, but with harder optional bosses, more sidequests, and more importantly, a deeper look into the next game.

For example, KHII Final Mix, has a longer somewhat different trailer of KHIII.

The same went for KHII.

But, before you guys get excited, this is Japan only. But the Second Final Mix has English Voice Acting, because the Japanese Kingdom Hearts Fanbase prefer that, with Japanese subtitles.

The newer scenes added in the Mix though, the ones that AREN'T in the original games, are voice acted in Japanese.

Anyway, the point is, if anybody here is a KH Fanatic, you should play them. PS3 import friendly, or magic swap disc for PS2.