I've never owned a GT game before... so..
I've owned GT4 since yesterday afternoon and my impressions are:
> Each car feels different; as for example i can rocket around LS much faster in an M5 than i would be able to in an E55 AMG
> The engine sounds are beyond great; not fan of the background and menu music though
> Graphics look excellent for say an NSX; other modelling i was less impressed by, but hey i play in car view anyways
>Diffculty level is good; AI can be menacing (at my expertise) and you can easy learn to shave seconds off a lap time
>The menus confuse me quite a bit; but i learn in time
>Car selection is excellent with Pagani, TVR and Ruf
Great game