I picked it up for the 360 and have it on the PC as well. I've always really liked the Codemasters racing games ever since ToCA Race Driver 2 and this is basically it's replacement. Their Rally games are also slick.
That said, I'll still play rFactor on the PC for it's realistic physics or Gran Turismo because I'm way too addicted.
rfactor is by far the best race sim on PC that doesn't have a monthly payment. Forza is awesome for 360 and I have yet to loose vs. someone while I am sober