Cnet has found postings on Apple's support forums with users complaining of an excessively yellowed display on the new iPhone 4S when compared to the iPhone 4. Is this a case of early manufacturing woes or just a subtle tweak?
Cnet says that complaints revolve around the screen being less contrasty/more washed out, with poor viewing angles to boot.
Posting messages at the Apple Support Forum, several of the users say that the screen looks washed out and that the whites look more yellow, especially when compared with the iPhone 4. Some say the issue is specific to the black iPhone 4S, noting that the display in the white version looks fine.
I put the white iPhone 4S side-by-side with the iPhone 4 and saw no major issues. The general screen temperature on the 4S was warmer and ever-so-slightly more yellow compared to the bluer iPhone 4, but the difference doesn't seem like a defect. The 4S screen seemed a bit sharper and more dynamic. And if anything, the viewing angles seemed better (though for the most part, the two phones were equal). Displays in iPhones and iPod touches have always varied in temperature and hue and that's what this seems like.
That said, there have also been issues with displays in early Apple devices. The first iPod touch suffered from a defect which made viewing angles terrible. And of course, the iPad 2 had that weird yellowing thing going on.