Just my two cents on this game: I got it today and I haven't put it down yet. If you like GT games, then I see no reason to pick this up, especially at this price.
I'm not exactly sure, but from my experiences, you can't get credit on the same game on the same platform for use at the same time. For example, I bought 2 copies of NFS: Shift for the PS3 and I was only able to use the $10 credit on two separate purchases instead of them combined into one $20...
so i just created a new account but it will only let me use 500 points towards a gift card purchase. then i tried putting in a game and it would only let me use a 200 points. i guess this isn't meant for people without the sony visa card because it states that those are the limits which bites...