The Kingdom Hearts series are critically acclaimed for merging the best of both worlds: Disney and Final Fantasy. However, Kingdom Hearts: Chain of Memories (CoM) doesn't really stand as a great example of this.
Chain of memories offers an enjoyable experience, but this is largely due to the presence of great Disney characters from great Disney movies. Unfortunately, there is no real NPC interaction, and the battle system is not that good at all.
The story of CoM basically comes down to trying to save someone, while losing your characters' memories on the way. As such, some at first sight inexplicable story elements will become more logical. The Disney movies are actually tied into the story in a somewhat odd fashion, which is also solved by the entire memory thing: they are just the main characters memories...or are they...?
Kingdom Hearts basically is a hack 'n slash RPG. From a fixed (3/4) top down perspective, you'll control your character in a visually 3D environment. This is basically how almost any 'fake-3D' adventure works on a '2D' system, which is the GBA.
The gameplay consists of running between rooms and killing shadow-like enemies ('heartless') on the way. There is no real -NPC- character interaction to speak of, and puzzle elements aren't present either. If you've defeated enough enemies you can level up by either increasing your health, your maximum allowable deck-size (both strength of the cards and number of cards count towards this maximum) or you could learn a special move ('sleight').
If you'll engage an enemy (or vice versa) the game will switch to a battle-screen which allows for real-time movement both sideways as up and down.
This battle system is the main weakness of the game. Yes, it is card-based, but that isn't necessarily a problem (see my review of Baten Kaitos). However, the card-system isn't very deep at all. The only strategic part is to create and update your deck wisely in-game. However, as the game doesn't offer a paper-scissors-stone system the strength of your deck is basically a number thing (and some minor magic stuff).
This really limits the strategic choices in the battle mode itself as well. But even more importantly, the battle system is a weird combination between real-time and turn-based, giving you no real possibility of selecting that one card you would want to play out against your opponent's current card. Believe me, you'll often be too late.
Instead, you'll be button mashing for the most part, which is a real shame. Some of the end-bosses are also insanely hard, and if you don't want to mindlessly attack simple enemies for hours just to level up, you'll have to squeeze out every tiny little bit of strategy the game has to offer (which isn't that much), and then still be lucky.
The characters look great on the GBA, but the environments are somewhat less inspiring. This is largely due to the fact that you're moving in room-like environments.
Overall, the DIsney and Final Fantasy characters are easily recognizable and are just looking great. The intro and ending movies are just superb!
It is safe to say that the graphics are definitely the best part of GBA.
The sound is pretty good, with sometimes even spoken stuff, especially in game ('Aladdin!', 'Genie!' etc.). But the music is often not taken from the soundtrack of the corresponding movie and often gets boring after a while.
CoM will take you a while to complete..unfortunately for all the wrong reasons; if you don't want to level up for hours if you'll face one of the stronger bosses at the end you'll still be playing for hours just waiting when you'll finally have that extra bit of luck that will let you be victorious.
After completion the game offers you to play through the game again with another character, and explaining more of the story, hence providing more replay value.
Kingdom Hearts: Chain of Memories is an enjoyable game. That is, if you like Disney. The Disney influences will let you keep on playing even if you're becoming to get frustrated by the game's flaws. Kingdom Hearts is by no means a bad game, but if you don't like Disney or Final Fantasy for that matter, you'll be better of to avoid this game altogether or at least pick it up cheap.