I finally got Mario Kart Wii yesterday. After playing it, it's definitely the funnest Mario Kart yet. I thought using the steering wheel would be hard but it's actually pretty easy to use. I also like the retro courses from past Mario Kart games, especially the ones from Mario Kart 64. Overall, it's a great game that I recommend you check it out.
I'd also like to point out that my Wii isn't hooked up to the internet, so I can't play online.