People are getting it all wrong.
I do give GT5 a -.5 only because they never announced such a thing. They showed trailers and made it look like every car was amazingly detailed. But they only focused on the cars that mattered. And whoever compared NFS Shift to this game shouldn't have bothered and hasn't gotten far enough in the game to enjoy it. NFS minuscule car list of 68 isn't even half of the 200 premium cars and in NFS Shift only about 10 of the cars were worth using. People complaining about 800 cars not detailed is ridiculous. The game wants you to use the premium. Your not going to be rolling in a 73 BMW 2002 Turbo through the whole game.
I do think GT5 needs to work on the customization part more, but this isn't about making your car look like it belongs in a HIN event this is about racing a real car without the kiddish amenities. Go play Underground 2 if you want that.
Damage isn't a big deal to me really. If you know how to drive then you shouldn't be crashing nor should you purposely bounce off the walls or other cars to gain placement. The game also implements penalties vs such action and will immobilize your car for a certain amount of time depending on the action you took its just people just haven't gotten far enough in the game to realize this. The game has a noob system built in for noobies that don't know how to drive then once you start actually becoming good and higher lvls then the difficulty will raise on you as it expects you to be actually good by then. Its a teacher system to help you learn how to get better at driving.
Weather effects is great and Forza doesn't have it so you can't knock them for adding it. Period.
Forza 3 was good it was fun to customize and race, but the game got horrifically boring as it was always the same race after race nothing special. And staring at your pretty car you customized only entertains you for the first couple days of playing then you start realizing how simplistic Forza 3 is.
GT5 is a game for adults. Forza 3 will always fall in its shadows as it doesn't focus on the big picture. Instead it follows the kids that came from NFS style racing.