You really believe that the foliage looks good? The obviously low res, 2D sprite foliage? And because I know Squilliam will say this, yes, I know GT5 Prologue does the same thing.
The cars look utterly fantastic though. I'll reserve judgment for the game's in-game race graphics until I see some real in-game race graphics and not something from photomode. Hopefully track detail is improved along with better texture filtering (something that was absolutely terrible in Forza 2).