I feel that this game has zero to no improvements over GT5.
I hate the fact that using a manual clutch is still a disadvantage and not an advantage. It's just impossible to shift quick enough with it, because you have to completely depress the clutch and then start to shift, and you can only start releasing the pedal when you completed the shift. Otherwise you end up in Neutral, and have to start the whole depress shift release process from start while loosing a ton of time. It's totally unrealistic. And it's exactly the same as it was in GT5.
But moving on, at least GT5 presented some challenges. In GT3,GT4,GT5, but even in the PS1 games GT1, and GT2 which I played on emulators, It was really really hard to achieve gold in license tests. Now it's a walk in the park. Maybe 7 out of 10 times I end up getting gold for the first try, that's not my skill, that's how low they set the bar.
Same goes for races, I haven't gotten to the professional categories yet, but until now, every race had an insanely high PP limit. They're easily winnable with cars that have 100 less pp than the limit.
The only real challenge in the game so far were the driving missions where you have a fixed car and target, but even those have problems. In many cases I end up getting gold, while loosing to the opponents. They should have disabled catch-up for these. Well honestly they should've disabled it entirely, I hate that damn feature. You race on the edge for five laps, but you make a mistake in the last corner and bam you loose, because no matter how quick you are, you can't build gaps.
Another thing I dislike is that they mixed up standard and premium cars in the dealers as far as I can tell there is no way to differentiate them. You only find out after you bought it. And since I like driving from inside view it's real annoying to find out that I just bought a standard car. Well you can actually tell by looking at the model very closely in the dealership, but that's just not the way it supposed to be.
Oh and why on earth do I still have to turn off traction control for each car individually? Why can it remember everything else but not that?
The fact that it downloaded an 1.2 GB patch when I installed the game on release day didn't even surprise me, just annoyed me, since it took more than half an hour to get into the actual game after inserting the disk.
On the upside there is improvement in physics You have a much more direct feeling of the cars and tracks, you can almost feel the tyres rubbing against the tarmac while understeering in an ff car, and you can feel the tail wanting to skid before it actually happens with rear wheel driven cars.
I also like the race loading screens, but that's just cosmetics I would trade in anyday for better clutch simulation.