I got back to Apple Store in Glasgow today to exhange my black 4s 16GB. The salesperson who was very friendly last time acted like a true salesperson this time.
I brought my old iPhone 3 with me and showed him the difference. The difference is immense. Again, he did recognize the difference. As many people here suggested, it is not noticeable in the first place. Plus, you should stop yourself comparing your device with other 4ss those potentially have better screen quality. If you comply with this simple rule you will be fine and will get used to yours after a while.
Anyway, the salesperson this time argued that I should not expect to see all devices with the same screen quality as they are not "identical", he said. Well, this argument obviously fails. Devices must be identical. At least the one I bought should has the same screen colors and quality with the those on the display. Please do spend some time and check the devices on the display with your own one. I am an Apple fan. So I do not go any further on complainting about my experience at the store. However, I must point out that he was not happy exhancing devices because he told me he must be selling them with contracts.
There are couple of important points that I want to raise.
First, I should not be spending time writing my experience. This is ridicoluos. Apple has to make sure that we are fully satisfied with the product.
Second, I should not be writing words like "better", "noticeable", "potentially" and "identical". We are talking about electronic devices which come out from mass production. These devices must be identical otherwise production line should be checked internally and externally. Difference on quality can never be an issue (nowadays you even never have a "better" BigMac at McDonalds, even they are made quickly by human beings. Whereas the components of these devices are electronically generated and enter into mass production).
I bought this new 4s to "upgrade" my experience with iPhone, in particular, and Apple services, in general. However, as far as the screen quality is concerned, my 3 years old 3G has a much better quality, brightness, and it is not yellowish at all.
I will keep my 4s for another 14 days and exchange it if I feel I angry one morning. In the meantime, I will wait and see what Apple will do about this issue.