Wii wheel is a pretty fun novelty, although I do prefer the Excite Truck style of steering. Actually, I pretty much just prefer Excite Truck, gawd if that game was online I would never stop playing...
Anyway, I always though MK Wii looked kind of terrible, and I was right. It's just feels off, hard to explain. The graphics are terrible and the colors seem washed out. The music is forgettable. Some of the stages are pretty cool but overall the game just gives off bad vibes. THE VIBES MAN, THE VIBES. Too many steps backwards. Compared to MKDS or even Double Dash it just feels awful. Admittedly they seemed to have somewhat fixed the blue shell problem by making it far less common than it used to be, but even so I would much rather play MKDS online. Too bad MKDS online sucks.
The only thing saving MK Wii is that its online implementation is fantastic. It does everything right, and it's blazing fast to boot. Getting four friends together in MKDS often took over 30 minutes to connect, which is unacceptable. If only Ninty could have gotten that to work...and I could have saved $50.