Well, I've gone through 5 Retina Mini's between myself and a family member now. All of them have had uneven white backgrounds. Meanwhile I can go on my girlfriends original iPad Mini and it's such a pleasure to have a balanced white screen on it. I actually prefer using it as I'm not getting distracted by any yellow. My dilemma has become wait a month or two and see if it'll get fixed over time but reading some of the backlighting comments has got me thinking this is a design flaw. Maybe they weren't able to fit as many lights near the home button. I'll probably go to my local Staples and get an original iPad Mini for $250 for their Black Friday sale. I'm just tired of product testing

I will miss how fast the Retina model is and how sharp text is. It's okay, next year I'll play the game again and hopefully they'll have gotten it together
To anyone still unsure if they should keep theirs I got a fantastic test for you: flip your mini upside down for 10 minutes of use. Open up couple things to test: a few white websites, notes, calendar, iMessage, type with keyboard etc. Then go back to the right way with home button on bottom. If you notice a difference and it's annoying, don't hesitate, return or exchange it. If you don't notice a difference or it's not a big deal, enjoy your new Retina iPad Mini
People should really stop posting pictures asking for people's advice. It doesn't matter what we think, you're the one that has to live with the device. Does it bother you? Can you live with it? Through the 5 Retina Mini's I've had, I've seen yellow on the bottom 1/4, yellow on the bottom left corner and now on the one I'm typing on its got a pink! on the left side, annoying!
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FWIW, is it possible my issue of the shadow is related to warm up? I've noticed that the shadow seems to fade after extended use.
Yes, I think so. We noticed after having been using the Mini for a while the yellow blended in better over time. A screen shouldn't need 20-30 minutes before it reaches optimum viewing pleasure though
Edit: typing all this out has made me realize how disappointed I am with the Retina mini. I've been flipping between holding it the right way with home button on bottom and upside down and the yellow near the home button and the pink on the left side has really stood out, definitely giving up on this generation of Mini. Bad parts, bad design or bad manufacturing. I've purchased ~25 Apple items in my life. This is the first return I ever did, to do 5 returns tells you something is bad.