I'm not a big racing game fellow, especially when it comes to sims, but I am now certifiably addicted to TOCA 3!
Can't really comment on how sim or arcade the game is...it seems pretty realistic to me, but doesn't go overboard. All I know is it's fun as hell.
Graphically, the game is very, very beautiful, even years later, it holds up very well...it could almost be released as a new game, hypothetically. Pretty sure I've crashed a few times just admiring how good it looks -- really!
But besides the controls and graphics, perhaps the best thing about the game is how varied it is and how much stuff it packs in. This game is loaded -- you get to use about every vehicle imaginable (each of which offers pretty unique physics), and the world tour and career modes will be enough to satiate your racing fix for months to come, at least.
Get it while you can!