I have the same problem. It just doesn't fit fit in my hand very well and my hand always hurts after playing Brawl even for a short while. It's hard to hold it with a finger on both C and Z (which I use heavily for Brawl).
Plus it's too light, but that doesn't hurt my hand 
# of games above 75 on Metacritic (including downloadable):
360: 241 DS: 144
PS3: 152 PSP: 126
Wii: 85









