Filament wrote...
It looks pretty sweet. Kinda want to get into it (the franchise), but there are a lot of titles on a lot of platforms though... among them, I just have a PS2, GBA and plan on getting a 3ds soon-ish. Finding the PS2 and GBA games would also be a pain. Hmm. It still looks really nice, though.
It's definitely a series I'd recommend, particularly for how it handles characters. Kingdom Hearts 1.5 for the PS2 has, appropriately, the Final Mix version of first game in the series, Re:Chain of Memories, and 358 Days/2 all on it.
So you essentially get three games in one package. Then KH2 is also on the PS2, so you'd have four of the... seven (so far) games.
Re:Coded for the DS is negligible. It doesn't add much to the story that can't be summed up in a few simple sentences, so if you really want to see it you could watch a Let's Play.
That would only leave 3D and Birth By Sleep, for the 3DS and PSP respectively.