I also had a chance to drive a G35 loaner about two weeks ago.
I have to agree with you guys about its awesome power but was not impressed by its built quality. It had about 5000 miles on it and there were more than enough rattles and plastic chatters coming from all over.
We all know that Infiniti's making superb hardwares and now they really need to work on their quality. Infinti engine/trany/design + Lexus quality= that's what I'm looking for.