It looks really good, the basic combat plays really well, the music was GBA-ified excellently and they even fit Simple and Clean in the cart...

Just the card system messes everything up, it's a complex system that demands a lot of your attention in the heat of the moment while you're also tracking where you are and what your opponent is doing (if they feel like showing you their deck anyways, sometimes you can just get nope'd because the game feels like it) and this is the core of the system, it's needlessly complex and really drags the game down. Same with needing specific map cards to unlock doors, I just started abusing emulator rewind and RNG manipulation near the end for the Map cards due to how needlessly frustrating that was.

The blocks of a portable Kingdom Hearts are there, but dragged down hard by an awfully tacked on card system that ruins the whole thing.