Looks like the game is very up to date with the anime, I saw some Bankai attacks in there. And looks like the story mode lets you relive battles from the anime as well. So I'm guessing all of the captains are playable, but the vice captains are just there to give you support items?
EDIT: The animation was the first thing that struck me as well. Sometimes it just seemed a bit stiff.
That animation is SHIT. Treasure don't u dare release this game moving like that. Some of the enemies in Dawn of Sorrow have more frames of animation than those characters. If this was a GBA game I wouldn't complain but we all know the DS is more than capable of displaying more fluid animation than that. Huge thumbs down.
Well, some of the animation looks jerky but I could live with it. Seems alot like Guardian Heroes to me and i'm still excited for it. And they seem to cover right up to current in anime. Still purchase for me.