I picked it up for a 10-spot about two weeks ago (EB was having a quiet clearance of the title, new), and the other day started getting into it. I've beaten a year so far, and started into the second.
My mind hasn't changed, I don't see why the battle system couldn't have been adapated for GCN-only play, even in multiplayer. It just makes some... odd choices, and I really don't see WHY you have to manage your action slots the way you currently do. (In Single Player, you physically stop and switch to a menu if you need to switch in a spell or item, in multi you must have to fiddle with menus in the GBA.) It just seems so unnecessary, and I don't know whether that's GDS's fault for relying on it, or Nintendo's for requiring it.
And it's a shame, too, because such a requirement looks like it holds back some people from playing an otherwise excellent party adventure title. Single player, at least early on, is a little too much "Jab, Fall back, Jab, Fall back," but I could see where it'd be great to have two or three warriors swarm onto an enemy while one manages the flask.
And the whole game... it really seems like they were experimenting with a lot of things, and even for their first GCN project, there's just so many nice touches and effects to it. Rich color and texturing, bump mapping, Star Fox Adventures-like fur fuzzing, cloth, hair and *cough* Selkies all moving around based on physics, the shadows, the reflections on the flask, the music transitions, the music itself... there's slowdown in a spot or two, and seemingly no AAing, but otherwise this is one of the GCN's prettiest games ever, I think. If the same developers who worked on this do the DS version, I really expect it to blow our minds versus what we thought the DS could do, graphics and audio-wise.
FF:CC seems like a great game (or at least a GCN showpiece) that most people got scared away from because it was saddled with such an unnecessary requirement. Take the GBAs out of the picture, and fix the Command System so that it doesn't have to be managed, and I think it would've been big. But what everyone constantly heard about was, "You NEED a GBA for every player," and "I can't play with my WaveBird in multi!" and all that.