Please note: This post is on the original Page Flip feature which was only available on some Kindles, not the enhanced all-apps and Kindles feature from 2016. For a review of the newer features, see this post from The Digital Reader.
I own (and love) a Kindle first gen Paperwhite. One of the things I lost switching from the Kindle Touch to the Paperwhite was the text-to-speech feature. I didn't like giving up TTS, but I knew about that ahead of time, so I was okay with it.
One thing I was not okay with was the original Paperwhite software did not support the next chapter/previous chapter function. The Touch had it; even the Kindle Keyboard (aka the Kindle 3) had it. The K3 used left and right arrow keys to move to the next or previous chapter, and the Touch used an up and down page swipe. When I got the Paperwhite, I was dismayed to find that up and down page swipes had no effect at all.
The Go To menu on the Paperwhite has a list of chapters, but it was annoying to have to invoke that menu when I used to just flip chapters with page swipes. I had heard the new (2nd gen) Paperwhite had a feature called Page Flip, but I had never seen it.
The other day I started re-reading an old Agatha Christie, Death on the Nile, featuring Hercule Poirot. It was the first Hercule Poirot I read on the Kindle, and one thing that used to annoy me is Christie would have Poirot sling out not only exclamations but whole sentences in French. The Paperwhite will translate highlighted text, but you have to have the wireless on, or (to put it in new Kindle-speak) you have to turn airplane mode off. Usually, I turn the wireless connection on only when I am downloading a book, but because of Hercule Poirot, I left it on for a couple of days, most of which was spent within range of my home wifi (my Kindles always have 3G, too).
Consequently, my Kindle got the new Paperwhite update! It now has several new features, most importantly, Page Flip. The (slightly fuzz) screenshot above shows what it looks like. It's even more like browsing a print book than the old function was. You invoke it with an upward swipe and it opens a secondary window on the screen. Within that window you can jump forward and backward chapters or pages and then either go to the new location or return to where you where. It is totally cool!
Merci, Monsieur Poirot!