I'm delighted with my Paperwhite. I compared it to my K3, and the k3 display just looks dirty compared to the PW, even with the cover light on.
Would I ever buy a non-lighted eink reader? depends on my finances and the purpose to which I would need to buy one. Seems to me the cost of my son's K4NT and its lighted cover just about equal the price of the paperwhite, though.