DiRT3 was still a great game. The problem was that it was just more of the same.
Anyway, I tried the demo. I wasn't impressed by the preview videos but it's actually pretty decent. They've basically taken the destruction derby mode from GRID and given the vehicles turbo boosts. I'll pick it up when it's discounted, though I'm certainly not going to pay full price.
The reality is that it does exactly what it says on the tin. If you're not into arcade system destruction derby then this game will not appeal to you. There really isn't any need for a cockpit view and in fact it would be a disadvantage considering that you can be side-swiped by other vehicles on the circuit of eight tracks, meaning you need to time your boosts and decide when to back out. Personally I'm hoping we'll see a sequel to GRID sometime soon, as I loved that game.