I recently finished the single player mode in SSBB and have now unlocked all characters. Even if you’re just into single player games, it’s definately worth buying. Subspace Emissary is engaging, the cinematics are wonderful. Although there is no dialog, it’s amazing how expressive they can even make a character like ROB. If I say any more, I’ll likely spoil it for you.
But if you have a Wii, this is one of those games you should definitely not pass up.