So I returned my Silver 64 GB 6S+ last week due to this issue and dark corners. Despite thinking that I was going to wait a while before getting another phone, I picked up one today when one of the local Apple stores got some stock.
At this time I gather I have seen more than 50 6S+ in the various Apple stores and they all have the blemish to one degree or another. The phone I just got still has a slight blemish, but the screen consistency is much better than the last I had. So far I would say that this is one of the best 6S+ screens I have seen.
To my eyes it seems that the 6S+ has a problem with the display not appearing flat. It bends slightly away in the bottom left and depending on what angle you are holding the phone the problem is more or less severe, with it being best looking head on. It looks like the glass is distorting the image ever so slightly, and I'm finding that there is something unpleasant and fatiguing about this display as compared to my old 6+ display.
As well as the distortion there is a slight color temperature and contrast change which makes it look like the gamma is too low.
I thought initially that I would keep this 6S+, but now I am not so sure. These things are $1300 here in Canada and it's not reasonable to be uncertain at that price. I feel that Apple will probably silently resolve this, but that resolution may leave current owners out in the cold.
Anyways here is a comparison pic. Like I said it's one of the best 6S+ screens I have seen so far. You can figure out which is which.
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