There really isn't much that can be said about Mario Kart Wii that you can't glean for yourself by watching the nearly-two-hour video of the game's 32 courses that wiinintendo.net put up last week. So here's that.
While actually playing Mario Kart Wii, I felt that the wheel is just totally unnecessary. That said, it works just fine, providing you with the same level of control you'd probably get from just the Wii Remote alone. But if you can't roll with the new stuff, the game's going to support Classic Controllers, as well as the GameCube pad. The key with the wheel is to hold it straight out in front of you and rotate it like an actual steering wheel, as opposed to tilting the remote, which is how most other Wii racing games handle steering. Also, the game appears to allow two players to get online from the same console, and which is a big win for all you splitscreen online lovers out there.
Other than that? Dude, it's totally Mario Kart, only it's on a Wii. Either that totally makes your insides go numb with anticipation or you're all, like, "whatevs." Either way, it hits North America on April 27.