Nothing I've seen, those antena issues were only rumors as far as I'd heard anyway, so I wouldn't put too much weight into it.
As far the quads, I don't think real app usage has much of an improvement over that. I've not heard of people who have issues with their phones in day to day usage, only for people who want to run synthetic benches, which are pretty useless anyway for real life predictions of usage. The U.S. Galaxy S3 is still considered a top of the line phone and it only has a dual core as well. Should be fine for years to come.
As far the quads, I don't think real app usage has much of an improvement over that. I've not heard of people who have issues with their phones in day to day usage, only for people who want to run synthetic benches, which are pretty useless anyway for real life predictions of usage. The U.S. Galaxy S3 is still considered a top of the line phone and it only has a dual core as well. Should be fine for years to come.