I could hardly wait for GT5 Prologue and the game was actually the reason for buying the PS3 instead of the X-Box 360. The more I am disappointed with the game. Really stands out are actually just the vehicle models. They are really unsurpassed and a joy to behold. But it is already thin. The tracks look nice, but specially disappointed the London route with the Murals optics. Then there is a lack of things like tire marks in the form of black lines that can be distinguished otherwise so wonderfully on the asphalt. Also similar effects like glowing brake discs One looks in vain. Then how much vaunted cockpit Perpektive. Who wants to see ne well-crafted cockpit perspective should GTR2 view for the PC to time. The looks in GT5 simply only bad.
For physics: The approach quite authentic, but the cars are much too kind and easy to drive. Even in professional mode without every several driving aids.
The Sound: To me the biggest disappointment! I leave the PS3 on n Fettes Devil running 5.1 system, but Doll's not. Forza Motorsport2 has a much broader spectrum of sound and far more authentic sound. This applies to both the engines and especially for the tires squeal as Nebenberäusche or accident noises.
Conclusion: For the quick game in between quite nice, but Forza Motorsport 2 is still by far the best console racing game. (Which is a shame, because then I lost a bet .. ;-()