I've had the japanese version for about 8 weeks now and imo it is excellent gameplay and the car's do act a bit strange on the joypad, but try driving your glanza around town or even track on a joypad.
i had a force feedback setup on gt4 and when people who were good on a joypad came to have a go they were amazed at the difference, steering wheel equals proper driving simulator, joypad equaled good times but they realised how much they bounced off things to get that good time.
so in my opinion steering wheel setup=good driving simulator and fun
Joypad setup= arcade game, bounce off things and think your doing well.
need to spare up some cash from my project to be able to afford the G25 then am online and kicking some TGTT ass