This is a high quality game. By that I mean it's stable, has good graphics, a nice size collection of cars & tracks and a reasonable selection of game modes.
I personally didn't enjoy the rag doll based game modes where you have to throw the driver a certain distance/direction. Felt a bit like a tech demo to me, to show off their physics engine - which by the way is very impressive! The whole car seems deformable, and the motion, as you steer, is very fluid. The car (and driver) feel very much a part of the environment.
I completed the career mode, but it requires persistence. The game starts off quite easy, but all of a sudden gets very difficult and you find yourself having to drive the tracks perfectly to win. To win, the game doesn't really reward the act of smashing into other cars. It's better to just clip them to spin them off or veer them into a tree/building; that way you don't loose your momentum.
Flatout 2 is really just an extension of Flatout 1. I can recommend them both.
To conclude; if you like muscle cars, arcade-style driving games, drifting around dirt tracks and a challenge, then this game is for you. If you like 2 or more of those things then you should still give it a try.