Reasonable, but doesn't qute hit the peak of GTR2
Physics - Great - 8/10. This is SimBin, and their previous products have all been of great quality and had great physics capabilities. The Race doesn't appear to advance too much beyond what was in GTR2, but what it does is tweak the feel of the cars, so that there's slightly more 'feel' for what is going to happen. Floor it round the corners, and you'll still end up back-end in the gravel... but you'll probably know why you did it, and how much less throttle would have helped you to not end up facing oncoming traffic.
Sound - Good - 8/10. There hasn't really been much development in the sound from GTR2, which doesn't really matter as the sound in that was pretty nice anyway. The music has been changed - there is now one piece of music that plays while in the menus. It's not bad, infact it's rather catchy, but I'd rather have multiple pieces ala GTR2. Of course, the cars in game do sound distinct, and the other vehicles, skids, crashes and such sound pretty much as you'd expect.
Overall Gameply - Very good - 7/10. The whole WTCC thing is very well done, but I feel there are a few things that they should have kept in that they didn't. The interface now feels 'dumbed-down' compared to GTR and GTR2. Some may like this, but I liked the feel of the GTR interface. While I realise that this is just a personal matter, and the same sorts of options are still there, I think this was a step backwards. Pit stops don't appear to have been implemented - at all - other than for stop/go penalties. I don't really understand why, as there is a pit-in system, but if you go into the pits, you just drive through. I've done this several times, in several different types of races, and it doesn't work. I'm pretty sure this is a bug, but reading on the official forums, it appears that most people have this, so it's looking pretty surprising that it doesn't have a feature like this. Those are quibbles though, as the racing, the two-race format, the weight penalties (Boy it's a shock when you first get a heavier (or lighter) weight applied) and the overall feel is pretty good.
Final Comments - A few performance tweaks (Especially to sort the weird stuttering coming onto the straights) and the addition of Pitting, and this game would score a good solid 8.5 or 9 - it's that good. I'm expecting that SimBin will patch these into the game pretty soon - I was a pretty early adopter (Purchasing over Steam, for a very competitive price - worked out to less than £25, including VAT here in the UK thanks to the strong pound), so first-release jitters are to be expected. There are a lot less than other games that I've purchased first-off, so I'm quite looking forward to this game getting the polish that being handed out to a few thousand people, who then scream at the developers for solutions, gives it. If you're not that bothered but want a good racing game, I'd say give it a month, maybe two, and get the game. By then it'll have settled down, matured, and be ready for general consumption