I have had a Kindle Paperwhite (with ads) for a month. I was a big fan of my previous kindles, specially the 4th-gen non-touch one. I preferred it to the Kindle Touch because it was lighter, the bezel was shallower, and it had dedicated page-flipping buttons.
So, why did I get a Paperwhite instead of the cheaper 4th gen after I sold my Touch? Because of the darkness.
Reading is an enjoyable activity, and I read almost anywhere, in the supermarket queue, while having breakfast, while on the train, and in bed. But in bed, the older Kindles required me to turn on the light, like a caveman.
Of course, I could read in my cellphone (small) or in a tablet (heavier!) or in a book (again, lights, caveman!) So, this was the logical choice.
It still doesn't have the buttons, and it still has a touchscreen which makes little sense in a Kindle (except for the keyboard) and the bezel is intermediate. But the lighting is glorious. Sure, it's uneven at the bottom. So is the lighting in a paper book while in bed (check it out). But it's not all that heavy (even with the fancy cover), and it has a similarly glorious battey life.
The cover is really great. It feels like leather/rubber, it's solid, has a deadgrip on the device, and it turns on/off when you flip it open/closed, so you don't have to hunt for the tiny button at the bottom.
The font selection is a welcome improvement, although none compares well to the default.
Also, WTF happened to the audio? Why is it gone?
So my ideal Kindle that will never exist would be: a 4th gen with frontlight and smart cover. A man can always dream.