I have a KPW from the 1st batch that was delivered on 2 October. This unit has a faint greenish "blob" that runs diagonal from top left corner to about the middle of the screen. It's never really bothered me to the point of returning it & going back to my Kindle Keyboard.
But I decided that I wanted to upgrade to the KPW 3G model & was hoping that Amazon had worked out the discoloration issues. So I ordered a new one & it arrived yesterday. Sadly, the screen on the new 3G KPW is identical to my WiFi-only model.