The cars are all fun to drive, and the different environments do genuinely call for different approaches. Racing on asphalt roads takes guts and faith in the grip you have. Racing on loose surfaces requires discipline, resisting the temptation to overstep your limits. And there's plenty of in between situations, like judging how much you can get away with cutting a corner on a difficult surface. Or even overcoming nature's obstacles, like night time and fog.
The critical flaw in the game for me is in the setups. You can choose suspension stiffness, tire set, tire pressures, etc. before every race, and everything has a very profound effect. So profound that if you get a couple of these elements wrong, you're wasting your time in the next race. Picking the right tire compound won't even put you in the ballpark. There's very little clarity in what effect the setup options have outside trial and error. And in a game like this you can never be sure they react realistically, ruling out a conventional understanding.