Great game, but not the game to buy a wii for.
First of all, the character selection is big, and has a huge variety. None of the characters are really recycled, and it can take some getting used to different characters. The unlock system is pretty cool in this game. Stages and other extras use a completly different system that works. The subspace emisary is a little long and boring. I hate to say it, but they could have done better. The stages are actually well done, I liked pretty much all of them. Finally, the smash ball is an interesting new addition that makes gameplay all the more interesting.
Now, I'll talk a little about the actual gameplay. I recently played the origional smash bros, and I was amazed at how strong the attacks are. They really toned them down, which they really shouldn't have done. With that being said, the characters are all still well balanced, and every fight seems like a fair fight. Some of the final smashes, like the starfox universe's are extremely cheep, and you just can't help but scream gay!!! at the person using them. Heh, anyway, the final smashes are a nice touch, and hey, nobody is forcing you to use them anyway.
Online play is...ok. It's pretty easy to connect to matches, and, even though there is lag, its bearable...sort of. Anyway, if you have friends with wi fi, and a copy of this game, its not too bad.
Here we go, lemme break it all down.
Graphics: 9.5 some of the best the wii has seen.
Gameplay: 8 Didn't bring back board the platforms, and watered down break the targets.
Sound: 9.5 Great soundtrack, and cool sound effects.
Overall: If you have a wii, no point in not getting this game, if you don't, well hey, get a wii, but not just for this game.