Sold my iPad 3 and paid off my mini.
The mini has a perfectly uniform screen. I went through 8 iPad 3's and even the last one wasn't good but I stuck with it. In the end, I have a very bad opinion of Apple now, because: 1) for selling such bad displays, and 2) screwing me (and others) over by making me lose 1/3 of the price I paid for it (the last one I bought was in july, so :/) by releasing a major update after only 7 months.
Though I love my mini, it sucks that it isn't retina, because it is a little jarring to my eyes when switching back and forth between various devices.
This is disgusting that Apple knows about these screen issues and yet hasn't seemingly done anything to fix them after 8 months now.
My screen issues varied, but most all of them had a disgusting yellowing in at least one of the corners, usually the top left as in the posters a couple posts up.
I Hope and Pray that IGZO fixes these problems, and it's just because of the current dual backlights causing these issues.
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I had a different experience with the Apple store near me. They were willing to swap twice, then they told me to get lost. So the rest of my iPad 3 swaps were at Best Buy and Target.
My point is more that in spite of the number of swaps that I did to get my current iPad 3 screen, there were none that had completely even backlighting. Most of them looked like the pictures from the previous page. If that's how they are still coming out, then moving to the 4 would do me little good, because I'd probably still end up with an unevenly lit screen.
I suppose I could give one a try, and then return it if it has backlighting issues.
They told me to take a hike, and that I was banned from buying anymore, because I admitted I had returned several through AppleCAre over the phone. All I wanted was to see my new iPad in store before I walked out with it.
GREAT customer service /s. Then Senior support couldn't even get answers from that store when they confronted them about how they treated me. I just gave up after that point.