At this moment in time fully 36% of the 55 respondents to this poll have indicated they returned their Paperwhite for a replacement. That is a HUGE number.
I just wonder how many of those stubbornly stick to a low PW light level. I have a hunch at level 22 of the 24 possible light levels most would not see ANY "defects."
Most purchasers of the PW probably don't even change their level from the default shipping level of 22 and are fully satisfied with their units.