I'll try to be brief, a lot has been said already. Yes, it's great game, looks good, nice driving and all...but...
It's quite an easy game, the biggest part of the game can be beaten with a few car upgrades and sloppy driving, a way to make it harder would have been to use simulation tires on all cars, maybe as a difficulty setting. The driving tests are hard to get on all gold, i haven't been able to do it yet. Other problem is having six cars on the track, it wouldn't be so bad if they actually stayed with you, but you'll be facing one car and the four others will be 2 laps down, lame. They don't know you're there, they ram into you, kinda sloppy.
You can't make an oil change during a tournament, and they make you do countless laps on the giant ring track with a slow car, are they sadists? And car wash? What for?
I found the rally portion to be more realistic than in gt2, the cars aren't doing 160mph over the bumps anymore, and that's great.
The car upgrades, adjustments, and track variety are excellent though.
Excellent game, but very overrated also.