i own the the first installment and i must say, word of warning, NOT IMPORT FREINDLY.
for those that think its just an ordinary smash bros style beat-em-up, your very wrong indeed. its a fantastic game that takes time to appreciate.
well it does play like it, but the main goal of the game is to unlock all the 'Komas' (or basically Comic strips). once you unlock one, at first it will be useless, you must 'unlock' it by filling in the gaps of that comic strips with the required koma.
may sound a bit confusing (and it is at first) but thats how you unlock more characters to the game.
think of it as a card game, you build your deck by completing missions which will reward you with empty Komas, then you must complete the empty Koma by fitting the required koma inside it.
Speaking of missions, the mission mode is basically the story mode of the game, and you travel the jump world through a world map process and each land/section will represent a theme. for example, the first area is One Piece, and so forth.
one dissapointing factor is that not all the characters you unlock are essentially playable, a huge host of them are manily support Komas (as in they may raise your speed, attack, defence, or what have you for a short period of time) or help Komas (Characters that may come in and atack or harm the opponent then jump out)
so once you have a deck, it will be displaye don the touch screen and you play by using the buttons to fight on the top screen. however this is where the deck comes into use. if you want to change to another cahracter on the fly, and say you have a Battle Koma Luffy. you just simply touch him, and you will instantly switch to him. or if you want some help, you just touch the help koma you have in your deck, E.G. Sena from Eyeshield 21, then he will come and do his thing and then dissapear. get the idea?
thats how i can sum it up basically, sorry for the very confusing description (its very late now lol) but thats the best i can do.
my opinion on the new Jump Ultiamte Stars has to be...GREAT!
mainly because this time it doesnt limit itself as it includes characters from more series such as 'Captain Tsubasa', 'Ultimate Muscle' and many more!