Played for only a little bit because it's Christmas, but here's a quick review of my impressions.

STRENGTHS
Unlockables: Something to strive for.
Balanced cars: different cars for different gameplay. Pick the one which has the best feel.
Good Tracks: They are a challenge and they have variations to keep them interesting. (what seems to be reversed, and different times of day)
Control availability: Has Wii Remote only, Wii Remote and Nunchuck, and Wii Wheel functionality.

WEAKNESSES
Long learning curve for control: This game is playable when you get used to it, but it eliminates the pick-up-and-play element for playing a friend on multiplayer. They will throw down the controller in no time.
1st time off the track means you lost: you are set back so far you might as well start over because you will not catch up. Annoying on championship races.
Sometimes has unsmooth gameplay: What Aronos described as a drop in frame rate is really annoying in a racing game where reaction time is a factor.
Name: There are no stunts. I admit that I went into this hoping for an updated version of Broderbund's Stunts (or 4D sports Driving), but there are only just a few jumps.