Is this the issue where when you especially look at a grey or blueish screen and if you move your eyes around you can see scanlines moving up and down the screen? If so this is the most annoying issue I have ever dealt with when it comes to mobile devices. I have had over a 100 phones and no matter what the model some have had this. Blackberries were notorious for this. I had it on one iPhone 3G and 1 4S. I just swapped them out and the replacements were ok most of the time. The problem is not everyone can see this issue. It was so bad on a friends iPhone once it made me nautios. He could not even see it. What I do now is if it happens is call Apple and have them send me a replacement and swap it out. If I take it to the genius bar they can't see it most of the time and think I'm crazy and wont swap. This was the first thing I looked for when I got my 5s. I though mine was perfect but discovered tonight my accelerometer and gyro are off about 4 degrees. Circuit board is not level with the case. I have one coming from att.com tomorrow I was going to refuse since I got mine at the att store yesterday. Ill return the lessor of the 2 but i will not tolerate any scan lines.
Other then that the 5S rocks and im very impressed.