A game package definitely worth more than the 50 bucks you have to spend on it.
Gameplay: The gameplay of Mario Kart Wii is unique and is virtually guaranteed to suck you in and keep you entertained for hours. The new trick system as well as updated mini-turbos adds a great sense of speed to this game. The online multiplayer is quite fun, and single player versions of formerly multiplayer-only modes such as battle mode were a pleasant surprise for me (though I am not sure if Mario Kart Double Dash or Mario Kart DS have included these since the only other Mario Kart I have played is the N64 version). Sadly, it does feel cheap sometimes when you are hit by lightning or a blue shell at the exact moment in time when you are hovering directly over an abyss of clouds.
Graphics: The graphics are what you would expect in a Wii game, about the same as Super Mario Galaxy. Minor details like glow and lightning crackling over your vehicle after being hit by a thundercloud are somewhat noticeable and are a neat effect. Sadly, a few of the retro tracks like SNES Mario Circuit 3 and SNES Ghost Valley 2 are extremely dull due to their 4th Generation roots. Especially the latter, as it is nothing but a wooden pathway above a bottomless sea of black nothingness.
Sound: The sound is also what you would expect. Music usually fits the theme nicely, and retro tracks still have the music they had back in their golden days. My only complaint is that the voices of the Mii's only use pre-developed voices based on their weight. My Mii sounds like a 3-year old toddler high on caffeine.
The Wii Wheel: The Wii Wheel is simply a shell for the Wii Remote. It is very comfortable, functional, and I prefer it over every other control scheme. The learning curve is generally around one grand prix, and it seems quite natural. However, in this game you shouldn't be using it as a reflection of real driving, since flicking your steering wheel up in real life isn't going to make your car pop a wheelie.