I played GT5 yesterday at the PlayStation Beta event, and as expected its really, really great. In 3D is lovely and works really well because they have gone for depth into the screen instead of stuff flying out at you, looks fantastic.
I played with a Lamborghini Galardo around the new Rome stage, which plays very nicely with great sets of corners which as always with GT tracks, flows greatly. I also played the new rally stage with the WRC C4 which again was great, and the day > night lighting is stunning. Nurburgring and Tokyo are brilliant still of course, but we know about those tracks
There was damage on the vehicles I drove/saw, although the Lambo only got minor crumples after a couple of big smacks. Not sure if the damage is less on the Lambo or that it requires many more smacks than a WRC car to damage, but it wasn't getting the same level of damage as some other cars. The Galardo had an interior, as did the Audi R8 I drove.
It's great though, and in 3D its very impressive (and still 60fps but with 15fps replays for now - they have obviously halved that from 30fps replays with all the post-pro, hopefully they will turn off post-pro so replays can go back up to 60fps).
You can drive the NASCARs around the city circuits

Its nice that the licence team haven't been cunty with the cars; they were at Codies in the earlier days.
Anyway, its awesome as expected.