Oh man, I was incredibly indifferent to Mario Kart Wii up until now. Just like Brawl, I have mixed feelings about the secret characters.
Funky Kong: LOL WUT/Epic win
Rosalina: Yes, yes, and double yes!
Diddy Kong: Hurray for the return of DK's little buddy
Daisy: HI IM DAISY was no surprise
Dry Bones: Nice to see him again. He's a decent grunt.
Bowser Jr: Again, no surprise here
King Boo: Him again? At least Petey's nowhere in site.
Toadette: Eh, don't care about her much.
Bowser Bones: Why not throw in Dr. Mario instead? He gets no love.
Baby Daisy: Oh come on now, how much more redundant can we get?
I hear the last hidden character is Birdo, but I've yet to to see any proof of it.