While KH1 had the many allies, and KH:COM had the cards, this game branches out to many other great things.
Many people will say that this game has too many cutscenes. That, in fact, is not true. Kingdom Hearts 1 had too little cutscenes, and this just improves upon the cutscene aspect. The mouth-to-voice coordination is astounding in most parts, and the actors are amazing. For example, Gilbert Gottfried does the voice for Iago, just as he had done within the actual movie "Aladdin". This brings a sense of remeniscence to people who have seen that movie, and it makes it worthwhile. Unfortunately, they mess this up alot by making Aerith's (Aeris's, for you 'Final Fantasy VII' freaks) voice sound like a soulless robot.
Thirdly, the music is breathtaking. The opening theme 'Sanctuary' is played with a reprieve at the end of the game, just altered slightly. They even brought in the actual main theme from Pirates of the Caribbean, "He's A Pirate". Most people who have seen that movie will recognise the theme right away, and, I predict, will visit that world more often than most.
In conclusion, the character design is almost flawless. The Disney characters included are colorful and vibrant, bouncy and joyful, as you would expect from them. The Final Fantasy characters that are included are somewhat darker, and do not show emotions such as the Disney characters would. This is also what you might expect. Now, my fellow gamers, I must leave this at that, so farewell, and keep playing!