I've noticed the purple line on the left side, and purplish tint on the screen's top-left, while holding the N9 in portrait. Barely notice the green line at the right, though.

I think it can be avoided by some clever software tricks, if you swipe up an app and view it in the task switcher, the purple line's still there. Some research on this should be in order - the screen has absolutely fantastic blacks but pales in comparison to my N900's screen in almost every other category.

BTW, the issue is really noticeable in the low-power clock mode. It seemed like artifacting to me at first, but upon closer inspection, it looks like a problem arising from the way Pentile does colors (also, you can visually see the Pentile matrix, which slightly disturbs me when looking at bright pages)

Too bad it's a Pentile display without the high PPI that usually comes with it.

The one on the right is definitely way too bright. You should be able to get an RMA for it.