Biggest difference I've found in battle mode so far is that you can elect to play smaller rooms instead of larger ones--this is particularly nice in single player, as I'd rather not be forced into large 8-player deals every time. And there's some spiked bomb that explodes blue instead of red...I assume this is a bomb that can't be kicked by enemies? Not sure yet, I might've totally missed this item in other games. Otherwise, the mechanics seem pretty similar...not sure if I'll be logging online anytime soon with it, so I dunno what's changed online, but the tweaks so far seem pretty good.
Actually, my favorite tweak is verrry subtle. You know how in the first BLand Touch, you had to pull out the stylus to start the game? This time, hit the start button in the opening menus a few times and it dumps you right into multiplayer mode. Go on, give it a shot.