While clearly not as good as the original two, it still has that Kingdom Hearts charm that makes it great.
Most of the game has recycled content from the first Kingdom Hearts. For me, this wasn't a big deal. As long as it is somewhat different from the original I was going to enjoy it. The bosses and enemies and some environments were the same, but the gameplay and the story were completely different.
I'll start with the best part. The story isn't anything extraordinary, but it is easily the best thing about the game. The story tells about Sora who travels up the Castle Oblivion in order to retain his lost memories. The scenes between Sora/Riku and the Organization members is very interesting. It really helps explain what really happened between KH 1 and 2. It explains more about the Organization and Namine. To me that was worth the money. The story was well put together, and very powerful. The music and graphics are exactly like KH 1 which isn't a bad thing.
Now for the bad part. The gameplay and level design ruined part of the game for me. Each disney world is separated into about 10 little rooms. While you do get to choose what is in each room (ex: save room, a room with treasures, or a room with countless heartless), there is no room to explore. I loved exploring the original Kingdom Hearts worlds. In this game it feels like your limited to small rooms in all these Disney worlds. Also the card gameplay was very hard to get use to, and even when I got use to it, I found it not very fun. In the game all your actions are represented on a card that is numbered 0-9. So each hit, magic spell, and recovery item, is used on each card. For example if you use a fire spell and the card has a 5 on it, and the enemy uses a basic attack with a 6 on it, then your fire attack doesn't work and then the enemy gets to attack you. At times it felt like random luck whether or not your attack would actually follow through. Now you can sometimes put up to three cards together to create a higher attack, but if you keep doing that then you loose your cards faster and they dont come back until the end of the battle. Like I said the battle system, takes a while to get use to, and overall I found it more frustrating that enjoyable.
Once you get use to the gameplay, it can be somewhat fun. Almost like a miniature Kingdom hearts game (hence it being a port of a GBA game). Sora's adventure is about 20 hours, and playing through with Riku is about 9 hours. Surprisingly though I found Riku's story to be a little more fun. It is worth your money only if you haven't played the game before, or if your a really big Kingdom hearts fan. If you want to play a Kingdom Hearts game, play the second one (the best one IMO).