I've been playing this for about 3 hours, and already feel I have enough of an impression to give a quick review - it's such a fantastic game.
Firstly, the handling and physics seem even better than before, and more complex. The cars feel suitably light when blasting down a straight, but the feeling of weight transfer and juddering rubber when cornering feels bang-on, so the light / heavy balance of the cars is realistic.
The way you control a sliding back end seems even more realistic than ever, with the perfect split-second time delay between your input and the car's response.
And inducing oversteer to powerslide is marvellous, so finely nuanced you can use it as a ploy sometimes to overtake from deep on the occasional corner.
Opponent AI is better - far fewer instances of cars ramming your rear bumper.
I fired up my Logitech wheel & pedals; it's not the top of the range model, but as usual, it felt fantastic right away - I really do recommend Logitech - they make awesome wheels.
Cars you win are exciting within a few events, plus you get a choice. I've got a 1970s BMW 2002 already, and a fascinating old JMC Javelin, among other jems.
Another thing; the in-car view is more playable than previously, or indeed than in any other racer I've played. I'm not sure what they've tweaked, but the view seems better, and it's compelling.
The framerate is the usual superb 60 fps at all times - even with 12-car races - and this makes for such an engaging game. The racing feels better than ever; again, the control of the car is so precise, so natural, that you can really get the most out of cars once you get the hang of them. You can drive smoothly, Jenson Button style, or aggressively, Lewis Hamilton style - the cars will react accordingly.
Even the bonus games are well judged; I played one where you knock down skittles, but unlike a "virtual" scenario, these are actual giant skittles on the road which are fun to knock over.
There's no negatives to report. There are very minor weaknesses in some of the scenery - trees perhaps better than before but still not as good as in Gran Turismo - and the main things missing are night racing and wet weather races; the latter in particular would be awesome with such a refined physics engine.
I applaud Turn 10 for fine-tuning an already marvellous game. I've played scores of racing sims over the years, and for me, this is the greatest ever. It makes me feel very privileged to be a gamer in this magical, golden era.