Despite no claims or indications by Apple, as an owner of every iPhone every single S phone has had a superior screen to the regular predecessor. Noticeably so, sometimes drastically. The iPhone 3GS had a much warmer display than the 3G, which some complained about but I found to be a huge improvement (the iPhone still uses warm displays). The 4S display had better contrast and overall much improved clarity (even other people noted it when compared to the 4), and the 5S display appeared more vivid as well as a contrast increase. Apple does use multiple manufacturers to manufacture the panels for the iPhone so there can be a difference even between two of the same model. Yet, in my experience or luck the S displays have always looked noticeably better than the predecessor model. Of course every iPhone has a superior display to the older model, but despite Apple not noting it I feel like S models always have more refined displays. Looking forward to seeing if they improved the black level on the 6s since (I.e. when the phone boots up) the color black looks like a backlit mess and there may be a new backlight in the 6s in part to support the Retina Flash.