I just ordered a 6870 a couple days ago and I got my dirt 3 and shogun 2 game coupons before the card itself. So I curiously dl'd it and I've got to say, even without max settings on my old card, it look FREAKING amazing! I'm actually just playing on med settings and woah its even more colourful than dirt 2, and I love the menu layout. Its like some slow motion car drifting, while you choose your races from some random triangle pictures. I can't wait until the card comes so I can boot up some eyefinity...
ANYWAYS... the game's awesome, depending on how much you play it, I'd say it was worth the $50, on steam.