Like many have already stated, the card battle system is not a bad idea, I just didn't like how it was done. I have never played the original GBA COM, only the PS2 ReCom. I'm sure it's better on the GBA but the PS2 remake, I can't stand it. I made it up to Wonderland and couldn't get passed the Queen of Hearts's cards soldiers, ironic I know. And even getting up to that point I wasn't really having any fun with this style. So when I hit that brick wall, I was not motivated to get better, I just looked up the cutscenes online and that was it.
I do like the concept of battle cards. I played the entire Mega Man Battle Network series on my GBA and it's incredibly fun. These two are actually quite similar in how they work in a way. The difference is Battle Network game gives you a time gauge to select your cards/chips you want to use and plan out your strategy while time on the battlefield is frozen until you are ready. And even if you do waste the cards/chips you selected, you do have a default attack and charge attack so you aren't just sitting there and dodging until your cards refill. ReCom you have to do all that thinking while the enemy is coming at you, and they can break your regular Kingdom Key attacks, forcing you to dodge and reload. You should at least have a wait command option while you figure out what you want to do. Not every gamer can think on their feet like that especially from transitioning from KH1 to this title, and your primary means to attack are now so limited.
ReCom to me is the most clunky KH game I have ever played, and the only title I refuse to return to. I'm glad KH still experiments with different styles for their side games. Melody of Memory is a huge gem of a game to me, and the anti-Chain of Memories. For those that are good at ReCom, you have my respect. I wish I could get into it, and maybe I could. But if I'm not having fun then why play? I already know the story, and have no desire to master this game. As tedious as some games like Days and BBS can be for me, I still had a overall fun time with them. With ReCom I simply didn't. Maybe I should try the original GBA version and see if I like it. I hope KH continues to experiment new styles regardless of this one.