I have to agree with Cobra_UK that the trailer isn't too spectacular. Yes, the cars are updated and look very nice, but they already did in GT4 and to be honest, I don't think I would notice the difference if I see those cars on a traditional tv resolution. I expected they would update the tracks and their surroundings, and by looking at the grass and trees next to the Nürburgring in the trailer, it seems like they haven't updated them at all. Are these still the GT4 tracks because the GT5 tracks are far from finished? I sure hope so. The physics seem identical, no sign of damage yet, no sign of cars getting dirty (not even on the snow tracks), not even weather or some night races...
Waw, we've got an animated pitcrew cheering at our car, not exactly at the top of my priorities list. The best thing about this trailer is definately the cockpit view with a real mirror, though there's no sign of a dashboard or steering wheel with animated hands.
If this trailer is what the final game looks like, we're ****ed. I won't buy a slightly updated GT4. Now what I think (and hope) is that they couldn't show us any of the tracks, damage, physics, etc. because none of these are quite ready to be showed.
I just hope PD still has some pleasant surprises for us in the future.