I have tested during hours and I can say that street cars are great, but high spec cars... I can't understand them.
Where in the world can you push full throttle with a Formula Abarth in second gear in tight turns? Formula Abarth is a low downforce car, light, nervous and stiff. In AC feels like a train, understeer, and infinite grip in rear wheels, every video you search of that car is from guys litelally FIGHTING with his wheels, but in AC feels like super glue, and It's really hard to slide with rear wheels if you do not unbalance the car purposely. BMW gt2 works in the same way... there is something wrong with grip in "competition" cars, I can't do donuts with these cars because they recover grip in a really strange way, even with totally cold tyres (just exiting pits). They start sliding, and then after a semicircle the recover the 100% of grip and wheels stop spinning and sliding suddenly.
And about Lotus 49... I can also say that is something really wrong with this car, that understeer can not be right, and It's not only understeer in fast turns, It's in 2nd gear too, when you push throttle you go straight, and does not matter how much are you turning your wheel, you will go straight, It's like a wooden plank. And in real life these cars had stone tires, and tons of engine power with no downforce, I'm not an expert, but this three things can not end in epic understeer and no oversteer when pushing hard during turn and no reactions when you aggresively turn your wheel during mid turn phase. I can only lose the control of this car at mid and high speeds unbalancing It purposely and doing It hard.
And now thing I like:
What I like of AC for now, is street cars, and circuit details, are great. You can have a really fun time with Ferrari, all street BMWs, and Lotus, ah... and KTM!. I can't say lots of things about them beacuse I don't usually race with that street cars, but I specially like KTM and Ferrari, just drove them during all day in all tracks, really great.
The UI is great, It's clean and I thing is clear and useful, about config lacks like FOV and that stuff... It's something I know they will add so no complains.
ABS for cars that in real life have It are really great too, and I have nothing to say aboout arcadish additions, I think it's great to have activable driving line and that stuff, more people to race with. I like rF2 "hard simulation" but guys... optional aids are welcomed for people who want It.
And graphical performance It's great too, easy to have high fps, need some improves in the edge of 60fps, because for me It's impossible to race under 80 fps due to stuttering and input lag. But about this, I think they will solve It. I have a GTX650 and I play at 720 with no AA, anisotropic x8 and low shoadows, no reflections. And I get 120fps.
I will wait for online, AI racing, posible career mode, is what I would like to see, It's where I have my hopes in this sim. Because for league racing and endurance I think will be hard for them to achieve the features rF2 have, I thing will be a must have both sims, one for his stuff, and the other for his stuff...