No issues whatsoever with colors blotches, specks or scratches. My screen is white. Not white white but fluorescent white. Until you've seen how a frontlit eReader works it's hard to describe. It's nothing like a LCD or book light.
I have only one complaint. I wish the text was darker but all Kindles suffer from contrast issues. I own a K4S that is worse, a K3 and K4 that is great and the PW I own falls in between the two but once you turn on the light it's not really a issue. It's so easy to add custom fonts (I have 10 installed) that you can fixed that problem easily by adding a darker font.
The Paperwhite is hands down the best eReader I've own. I currently have 5.
I should mention the higher resolution is just breathtaking on the PW compare to the K3 or K4.