Before RBR I was playing Colin McRae 3 and then moved on to 4 (had to play the europe version on my hacked ps2) and both were good. I started with the initial frustrations in RBR but it just takes some time to get used to the feel of the game. It's a lot less forgiving.
I'm still waiting for Forza 3, even though I don't play Forza 2 much (well I play, but I paint cars instead of racing) and I need to get back into some good online weekend racing leagues. I did a lot of forum time trial racing in GT2 and GT3 and didn't play much of GT4.
But back on subject... Dirt 2 does look amazing. But I still feel it will be more arcade to apeal to the masses. Unless they do what Forza 3 is doing and have newb assists to start, and you can turn everything off. But it still comes down to the physics and how the cars drive.