Good morning everyone, or in the case of our friends around the world, good afternoon or good evening. I would like to offer my perspective on this. Of course it's ok to disagree, but give this some honest thought. And yes, it is long, but I want to offer up a perspective that may help others.
My background: I am a full-time professional photographer that specializes in action sports, wildlife, and adventure-lifestyle photography. I travel around the world on commercial assignments every month. I am not the all-knowing authority or proclaiming that I am right at all costs, but keep in mind that color management and a deep understanding of the light spectrum is rooted in what I do for a living.
Here are some random things to take into consideration when evaluating the display:
The iPhone 7/7+ has a far more accurate color space than any other smartphone on the market today. It is supposed to be calibrated to the same standards as the cinema industry and to achieve this, the kelvin temperature has to be calibrated to a warmer temperature than what most people are accustomed to. For the uninitiated, a warmer display (or lower kelvin temperature) tends to look more yellow, whereas a cooler display (or higher kelvin temperature) tends to look for blue
and more bright.
A good majority of pictures I've seen here and in other threads are nothing more than a warmer screen when compared to their iPhone 6/6s series phone. In the majority of cases, this is normal. I'm not saying that every phone is perfect or there are zero issues out there. What I'm saying here is many people are panicking or worrying unnecessarily just because their phone appears to be warmer, when in fact, there display is just as it should be.
Be very cautious when evaluating pictures on the internet. Here's why: unless you manually set the white balance (on the camera you're taking a picture with), every camera in the world will automatically determine what it thinks the white balance in the photograph should be. You would be shocked at how often auto white balance is off and can skew the colors you are looking at in a photograph. Believe me, I know this and deal with it every single day. Neither of my $6,000 camera bodies are white balance and color accurate every time. I am always tweaking the white balance in post-production to align with a calibrated white balance and color-calibration target. I can take a picture of your phone right now and tweak it to look any shade of yellow or blue that I want. I'm not saying that anyone here in intentionally doing that, but I can guarantee you that your camera is.
To take this even further, the light your viewing your iPhone with plays a large role too. Are you evaluating your phone in a room with light bulbs at 2800 kelvin, 3500 kelvin, or 5000 kelvin? Are you in the sun or the shade? So many different factors play into this and will change the apparent look of your display. (And this further tricks the camera when it is taking a picture with auto white balance.)
Now let's look at unevenness or blotchiness. That is not normal. However, there are two camps in this thread that strongly disagree with each other on how glue may or may not effect the display in the very beginning of the phone's life. Setting aside the differences of opinion on glue, let me offer this: does it hurt to give it a week and see if things change? In many cases, most people can't get a replacement that fast anyway. And besides, Apple is not going to abandon you at the 10-day point or even the 3-month point. Give it a few days and see what happens.
It is also very important to give your eyes a few days to adjust to the new display that is warmer than what you are accustomed to. More so than any potential or possible glue issue, it's most often your eyes/human brain that need to adjust.
If your phone continues to have a blotchy or uneven color uniformity, by all means, definitely get it replaced! No manufacturer in the world produces a perfect product every single time. Ferrari, Hasselblad, Apple, Rolex...they all have the occasional defect that comes off the line. The difference with the companies I listed is it does not happen as often as the industry average. Nor does it happen as often as an internet forum would leave you to believe.
And that is why I'm investing so much time in hanging out here and typing this out. Humbly-spoken, I am deeply involved with this subject matter because it is a huge facet of my job and it pains me to see the mis-understandings that often take place or mis-information that might be unintentionally spread around. So that is my perspective. All I ask is that you consider these things when you're evaluating how your iPhone's display works. And by all means, if it's bad, hop on up and get yourself a new one!
Happy to answer any questions people have and best wishes...