My experience (with controller) so far:
First I tested some street cars, stock except for tires. (I usually use SM tires on most street cars) Everything feels more nuanced, there's more body movement and weight transfer and driving indeed feels more like IRL in my opinion.
Also, driving without ABS feels so much better now!
Next I took a completely stock F-150 around the ring, to see how lower tier tires behave now. The F-150 comes on CM tires and the lap definitely wasn't fun. Almost crashed on three occasions.
Not sure if it's just this car but I'm pretty sure that the F-150 on those stock tires didn't feel that bad before the update.
Next I wanted to try some track builds. I started with my swapped Twingo, which was easy to drive around the Ring before the update. Crashed at Hatzenbach. Tried again, crashed again. Tried a third time, drove extra carefully, crashed again. Absolutely undrivable!
Then I tried my 300SL track build and was expecting the same, because I thought that the old tunes just don't work anymore and need to be updated because of the new physics.
But: The 300SL works fine! I did a pretty quick lap on first try without struggling once. The car is as amazing as it always was!
So, overall I like the new physics and feeling, but one car working absolutely fine with the old settings while others are almost undrivable and the bad experience with the stock F-150 confuse me a bit.
Of course that's just my first impression, there's much more testing to be done. Didn't even try any racecar yet.
Oh, btw, the Kart feels much better now! Before the update, on Nordschleife, any contact with grass or a curb was a death sentence. That's not the case anymore. You can recover now from getting on grass and curbs also are no problem.