I bought the first iPad on the launch day. After a few day usage, I found that the top left corner is greenish and the bottom right is pinky. That's so obvious that the "genius" who was checking my iPad immediately decided to give me a replacement and said he had seen a similar one before.
Then I got the second one, this one is much better. But, when I open a safari page, not the top of the screen, where the url and bookmark bar are located, the left part of the par is yellow/grey while the right part is blue. It's obvious when you see a transition in the bookmark bar from yellow to blue...
I heard lot of people calling others OCDs, but the only thing matters is what you get and what you feel. Once you notice the unevenness of the screen, especially something that obvious, you will want to exchange it.
Of course I know that iPad is built with a consideration on cost and mass production. So I went to apple store in NY, Soho today. And I saw some of them are better, and some of them are just like mine, which has a yellow/warm to blue/cold transition on the bookmark bar.
So I realized that the perfectness we are looking for, if you call an even screen perfect, is not in the requirement of QC of Apple. So it will just depend on your luck. Then I simply returned it and get my money back.
Now I will just be using my MacBook Air/Pro and the first iPad.
If it's that hard to find a screen that meets my standard, then I just gave up.
I dont' want swap it more than once...
Last comment, I sincerely hope Apple can improve their screen or use Super AMOLED on the next gen ipad, since the introduction of hi-def screen makes long time reading on iPad possible, then there are more and more people care about the evenness of the screen when seeing webpages or document when the background is pure white most of the time....