Mine works, played for 2 hours on various modes (even got Mr. Gn2Dlnd to play lol) and no problems. Played online some also
How did you know if it doesn't work? Does it glitch up while playing, or just not load to begin with? Anyway, good luck with it!! It's totally fun, and let me know if you want to friend add me -- there's DIFFERENT friend codes for SSB than your regular friend codes for the Wii. Yeah, I'm serious :-\
It tells you of course in game, so if you want to play with a specific friend it'd just take a phone call of code exchanges. Also you can watch games and bet on characters, or play random games with random people. Plus there's regular smash bros AND a "storyline" game
Plus..... well there's a lot more too. It's pretty crazy.
Word of advice though -- it does NOT use motion controls whatsoever, so do NOT use the Wii + Nunchuck setup. It's ridiculously difficult. The best setup for me is actually the Gamecube controller, but it doesn't make cutesy noises of course when you choose a toon.
The sideways Wiimote works great tho too (I haven't played yet with the classic controller). Really fun game!