Finally got a chance to play some proper GT5 this weekend, with a G25 and a playseat. Session wasn't all too long though, so my impressions are limited
Graphics/framerate is actually worse than I thought, I expected framerate dips but not the CONSTANT framedrops I experienced in pretty much all my races. And holy shit, the tearing is pretty jarring when in cockpit mode. It's kind of weird how this was acceptable at Polyphony after the smoothness of GT3 and GT4. The lighting is mostly nice, but there is some overuse of blooming like in Forza3 in some places that I didn't expect.
Handling is a mixed bag. The driving is about a million times as engaging as in Forza, part of this is because of the FF wheel of course since I play F3 with a controller, but there is definitely some weird areas. Vehicle dynamics feel/look better, body roll in particular. But wtf the brake balance. All cars have wayyy too much braking force on the rear wheels by default, I kept locking up the rears and spinning after almost every hard braking zone, even in smaller shitbox cars. After a while I adapted and started letting up on the brake force towards the end of the braking zone, but it was really hard to time since it just happens all of a sudden without warning. Even setting the ABS to the lowest setting seems to make a WORLD of difference to this and the general handling of the car. Collisions sound AWFUL and look kind of weird, but I do like that you actually lose control because of the weight transfer and can get into some serious fishtailing. Loss of grip on kerbs feels really good, and the cars have a lot more momentum than in Forza3, where you pretty much never spin out, ever.
Sound is pretty bad. Collisions sound like an artillery gun going off in your subwoofer, engine sounds are terrible and tiresqueal.wav is still looping away at every turn.
All in all a nice tryout, would buy for timetrialling if I was single and a millionaire etc etc.