Kontrols
The driving experience in Mario Kart Wii is similar to predecessors, except for the new expectation of tilting, jiggling or thrusting the Wii-mote around during gameplay. There are several different methods of control for the game, so let's go through a nice rundown:

Wii-wheel: The game comes with a free Wii wheel, which would otherwise have set the buyer back ~$15. The Wii-mote fits conveniently into it, and a loose, clunky rectangle on the back lines up with the B-button to make everything accessible. Using this lightweight, white plastic torus, (I'm sure you'll be able to personalize it very soon with skins, images, perfumes or whatever Nintendo dreams up for a little more cash), the experience feels a little like driving in a tiny, invisible automobile on a frictionless road located no specific distance below you. Tilt it right and the kart turns right; left and it turns left. But if that's not enough fun for you, there's more! When using a motorcycle, tilt the wheel up to pop a wheelie (this gives you a small boost in speed, but makes you susceptible to being stunned by opponent collisions and you have less turning capability while suspended on one tire). If you're driving off a jump, give the controls a quick shake and the character does a trick in the air, followed by a speed boost upon landing. Different shakes result in different tricks, it seems, but so far I can't figure out how to get any dirty gestures out of anybody. (I mean, wouldn't you want to "express yourself" at someone as you leap past them after they pegged you with a red shell while driving down I-40?).
A seasoned veteran of Mario Kart will probably get frustrated with the wheel, and might even toss it altogether after trying the other setups. The main problems are that it's difficult to drive in a straight line (it slows you down especially while wheelie-ing) and timing on drifting is tricky -- you can easily accidentally start drifting the wrong way if you're too fast for the controller. Shaking the controller (to recover from spills, do tricks over jumps and pop wheelies) can make it hard to maintain a direction as well. The bottom line is that no matter how fun it might be to play around with for a little while, the Wii Wheel raises the degree of difficulty to master the game to an incredibly high and frustrating level to the point of not being worth it. (Note: removing the Wii-mote from the Wii-wheel gives the same basic control system; I guess it's just not as Wii-cool.)

Nun-chucks: Not included with the Kart game (but available for purchase at your local gaming supply store) is the nunchuck option, which utilizes a second hand controller that attaches to the Wii-mote via a plug-in cord. In this layout, the player doesn't physically turn right or left, but rather uses the analog stick to direct the vehicle. The Wii-mote side still controls wheelies and jump tricks by quick upward tilting of the front end or giving it a little shake. Using items might require some dexterity of the fingers, but of all the choices this is probably the most ergonomic method of control.

Classic or GameCube Controller: For those that really can't handle change, be (somewhat) reassured. You can still do sufficiently well using the old models. However, when using this set up, shaking the controller like a monkey on acid will secure nothing but the ridicule of anyone watching you. Gameplay won't be affected by your physical outbursts (which might be good news for control throwers… you know who you are). There is one major drawback for those looking for a GameCube like experience: Mario Kart Wii changes the fundamental control of the GC controller by changing the button layout… and it is impossible to adjust which buttons do what in Mario Kart Wii. If it were one problem or the other it could go without mentioning, but the combination makes using the GC controller less satisfying for fans of the Mario Kart Double Dash.

The inability to adjust the controls continues to be a serious oversight in the Mario Kart series. There are small tweaks that would go a long way for all control schemes, and it doesn't make sense anymore not to allow the gamer to tweak the controls if he or she wishes. We can build it better. We have the technology.
On the SNES it was mostly about the racing, the control of your kart at high speeds, with the occasional item that may help you out, may not.
Now, it seems that the the racing has been completely replaced by random chance and all at a snail's pace, even in the 150cc cups.
You can be finishing 1st, 1st, 1st, then 12th???? in a cup. Why? because of constant attacks that are so unlikely and random as to be frankly mind boggling.
The blue shell, seriously, what's the point?
The wii wheel? OK, until you get an itch and then you are buggered, there's no chance of a quick scratch without you finding your self well off the track.
Such a great disappointment.
I guess if I was 12 again I might have the time an inclination to take on this game but I really can't be bothered. What's the point? Your hard work will just be undone by a series of unlikely events.