The demo just came out, and GWN already has a full review to read while you download.
"Of course in this day of Forza and Gran Turismo, the real key in any racer that aims for realism is how the cars "feel." As fun as DIRT is, this is one area where I found it lacking. The Mitsubishi, Subaru, and the buggies don't seem to have a lot of difference in terms of handling and general driving experience.
Once you've tooled around in each for a couple of laps you get the feeling that they might as well be interchangeable. Handling itself is sublime as it has always been in Codemasters' racing games, but the cars (at least the three in the demo) all handle in the same sublime way."