My last trip to Vegas, I did the exotic driving experience. I ran the Ferrari Italia 458, Lamborghini Gallardo Superleggera LP570 and the GT-R. If you would have told me, I could take any car I wanted home with me; I would have taken the GT-R, period.
I don't know of said problems with the GT-R besides the tranny, which is due to excessive launches which was rectified in 2010. The only other problems I know of involving the GT-R are from people modding them. I mean for goodness sake the GT-R's motors are only made by 8 people in the world and every engine is built by 1 guy from start to finish in a hermetically sealed room. Unfortunately, I don't think Lexus can make that claim about the F.
If you only drive fast occasionally, save your money and stick with the F. If you drive fast a lot and attend track events, get the GT-R. It's just that simple lol.