I Didnt find it dificult at all, Ive unlocked all the costumes and extra characters now can finish the game in less than 5 mins with certain characters. just the end boss thats a bit annoying, her fighting style is very cheap and annoying, but quick moves and the odd charge attack will sort her out in no time. :)
oh and order the big Joystick from one of the importers. its so much better than the pad