Carbon's audio is top-notch. EA Trax always have some great tunes to offer, but the star of the game's sound is the voiceovers. The police scanner has very realistic chatter, and the conversations you'll share with friends and foes alike is well written and nicely voiced.

Graphically, Carbon on the Wii is at about current-gen levels. Few of the images will knock your shocks off, but it's a pretty game with very few flaws. The camera pans are cool, and it daringly takes on nighttime driving and succeeds.
Need For Speed Carbon on Wii has all the ingredients that made the other versions great. Because of the wonky motion control, however, I recommend you skip it in favor of more traditional means of control. Mastering it is just too big of a hassle, and every other platform's offering has better multiplayer options anyway (a little thing called online).