My wife has a 4S and I have a 5, and the colors are about the same although the 5 looks a touch more vibrant.
The high level story is the same though, the iPhone 5 tracks closer to the ideal than any of the other devices.
The color quality and color accuracy have improved substantially. The iPhone 5 received a Color Gamut and Factory Display Calibration upgrade similar to the new iPad. While its not quite as accurate as the Excellent calibration on the new iPad, it is still Very Good and probably more accurate than any consumer display you own (including your HDTV), unless you have a new iPad.
If you can't tell any difference between the iPhone 5's display and the 4/4S, either you need to have your eyes examined, you got a defective phone (highly unlikely), or you're just ßull****ting.
http://www.anandtech.com/show/6330/the-iphone-5-review/15
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http://www.displaymate.com/Smartphone_ShootOut_2.htm
I stopped actively looking for scan lines whenever I use the phone and I barely notice it anymore. I just got tired of exchanging phones and honestly the colors, tint, etc are all good on this screen.
I completely agree I had scan lines on my last two emplacements had them swap it out again to get as term that finally didn't have the issue but had this issue instead Image
backlight bleeding which makes the whites really bright in that left corner and black background is out rid the question because all I can se is a yellow tint
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They don't manufacture the screens but I wish they would stop buying them from whoever is making these flawed ones. They have about 3 different sources for LCDs. This has been ongoing since at least the 3GS, on which some screens had horizontal scan lines.