The draw of Kingdom Hearts is the mash-up of Final Fantasy characters and Disney characters, yes? Hopefully you have a second answer, because the multiplayer demo of the latest game in the series offers neither legendary roster.
The Nintendo booth at PAX is showcasing a few DS games, including this month's Kingdom Hearts 358/2 Days, a portable adventure set between the two major console Kingdom Hearts games. I didn't mind that the man demoing the game said that Square-Enix doesn't want to reveal much of the story. I didn't understand the story of Kingdom Hearts 2 anyway.
I asked to try the co-op multiplayer mode in the game, a wireless mode that can connect up to four DSes locally. Wikipedia informs me that Disney characters are unlockable in this side mode, but all the demo gave me access to were the black-robed members of the series' secret society, organisation XIII. I chose to play as Lexaeus. The Nintendo rep adjacent to me chose Roxas.
The game's controls are primarily button-based. D-pad moves. Face button jump, attack, and activate spells and items from menus that pop up while the fighting continues. The combat is in real-time, without pauses. The combat is far less spectacular on the DS than it is on the PS2 versions of the game, where nearly every swing and combo emits a flourish of special effects.
(Screens not from the multiplayer mode — there weren't any in Nintendo's press kit.)
The multiplayer mission we played had our two organisation XIII guys hunting for a robot-looking character called the Sergeant. We had to fight through a few areas outside and then inside a castle. The critters we faces and the environment in which we fought bore no resemblance to any famous Disney or Final Fantasy lore. That made the experience feel generic, as flavorful as a Peanut Butter Cup without the peanut butter nor the chocolate.
The gameplay was competent, but the level design was bland: Clear an arena. Move some stones onto certain spots on the ground to trigger the opening of a passageway. Fight down the hallway. Find Sergeant and slay him.
The whole thing felt like a proof that Kingdom Hearts' basic systems can support multiplayer, but showed no sign that the most colorful aspects of its fiction have been applied to that co-op structure. It can be done, but, in this game's demo it didn't look like it was being done.
For the record, the game's single-player demo included characters from Aladdin. The Disney and Final Fantasy magic is there. But if you want that kind of thing in multiplayer it doesn't seem like you'll find much of it. Fantasies of player one as Cloud and player two as Mickey will have to wait.