I am testing both a 6 and 6+ to see which one I prefer, but both have noticeable screen issues. The 6 is noticeably darker in the top right corner, and the colors look a tad washed out compared to my 5S I had. The 6+ has an annoying graduating color temperature from warm on the bottom to cool on the top. It's not a significant deviation between uniformity, but it's still noticeably so. I've also sold several 6/6+ as I work for a rural cell carrier and have been seeing largely the same things. One 6+ was so bad I felt bad for selling it because it had a noticeably darker band on the top edge of the screen. I'm sure there are other threads on this but I just wanted to express my own disdain for these devices. I'm not even sure I prefer the design over the 5S, and I've never felt that way with any iPhone. This is coming from a very long-term iPhone/iPad user (I've had every iteration of both).