Frankly, I like the "softer" white that came with my white 4S. Don't know if that's the yellowish tint that people are complaining about. It's not "yellow," and I don't know at what degree of yellow that people are experiencing, but maybe my eyes had gotten accustomed to the color already? When I changed the brightness from default to 70%, the screen does get slightly "whiter/bluer" so I don't know if that's a quick fix to "yellow gate."
I had the 3G since it came out and i still have it. And yes, it does have a cooler/bluer screen, but after awhile of use, my eyes starts to strain. Back when i compared my 3G to my friends 4, there was an on obvious brightness difference. His was "dimmer" when we had both phones set at 100%.
I don't really know if my phone is affected or not, but based on my current experience, i am fine with how it is. Battery is also fine. I've charged to 100%, left it on standby for 9 hrs, and it was at 98%, with slight use of email and web surfing. I must be one of the lucky ones.
With the new 4S, I've noticed that I am experiencing less or to no eye fatigue over long periods of use (ex. Emailing, reading, etc...). Honestly, If I didn't have my old iPhone to compare with, I wouldn't even have noticed a difference.
I googled an online contrast tester site for iPhones, and my results were fine. Even tested for any dead pixels, too. Passed that with flying colors.
Maybe some of you might want to check it out for yourself.