Just finished the demo, so my impressions now:
The car is a Corvette C6, so handling is a bit twitchy and you have to steer with your right foot a lot. Personally, I like Corvettes, so once I got used to it that was no issue. I don't know the track the least bit; I did 10 laps and the fastest I got was a 0:57.9, but I have no idea if that's a decent lap or not. I'm thinking not, because I was a real wuss through the chicane. I couldn't get my braking point figured out at all. The next two corners were pretty much flat - they almost reminded me of the Lesmo corners at Monza, although slower and with some elevation changes.
I thought the physics model seemed really good, and once I realized that setting damage multiplier to +100% makes your car a Ming vase (realistic for a Formula car, probably not so much for a stock car) I didn't have too much of a problem. Since the damage model is also pretty good once you've banged the car up once you're going to have problems for the rest of the race.
The biggest problem I had actually was a bit of an embarrassing one - I'm so used to Formula One racing with paddle shifters and a wheel clutch that my manual shifting is really pretty terrible now. I don't know how many times I spun the car because I shifted down without properly engaging the clutch. I'm also used to Formula brakes, so I went straight through at the first corner and into the tire wall
I thought the AI was good - I did 5 laps alone for practice, then a 5 lap race with the AI. I started 17 out of 22 (random grid position, not my fault) and finished 5th after a spin. I had set the AI down a fair ways from 100% though, so it's not a fair test of their speed. They do actual overtaking moves, which is nice, and they don't yield position like babies, unlike some other big racing games.
On the whole, I liked it, and I'll probably get it later, assuming the open-wheel support is there. I think I saw some screenshots of Formula cars when I was on their website, so I'm assuming there's at least some support. Hopefully also a few Grand Prix circuits - I'm partial to Spa, Monza and Suzuka, so I'd like to get at least one of them in there.
EDIT: I looked up the track - Lime Rock Park - and apparently the lap record is 43 seconds
So I guess I'm rustier than I thought...
ANOTHER EDIT: Something I forgot to mention initially - the Force Feedback in my wheel (G25) was a bit dodgy; the feedback was detailed and good, but very weak. I couldn't figure out how to turn it up to get any real feeling, so it sort of felt like I was floating on the surface. Does anyone else either a) have this problem or b) know how to fix it?
PS: I'd never heard of Battle of Stalingrad, but it looks pretty cool. I don't do flight simulation nearly as much, though - I think it's fun, but I don't have good equipment for it.