I just read two novels on it (see previous reviews), so I now have a sense of how I feel about the origami case (meh) and the page turn buttons (a definitely improvement over the Paperwhite's lack thereof). Initially, I had a habit of hitting the back button whenever I put the reader down. I had to consciously hold it in a slightly different place to avoid that. Then I kept getting sucked into left/right expectations and paging forward repeatedly when I meant to go back. There is a period of adaptation, but it does not feel onerous, and the experience gives me hope that when I am adapted it will do what I want it to without me having to think about it, which is more than I can say about the Paperwhite with the whole footnote problem whenever trying to page forward in non-fiction.
I checked it against my existing (I think original) Paperwhite (I didn't see a compelling reason to get a later generation). In case, it is lighter by slightly more than an ounce. While the screen size appears to be identical, the overall dimensions are noticeably smaller.
Charges well. Holds a charge fine. Does what I expect it to. Has a crazy crisp screen. I mean, really amazingly crisp.
It's always hard to know whether a given upgrade is worth the money ahead of time, but I sure don't regret this upgrade one teeny tiny little bit. I am overjoyed.