Ever since Amazon launched the Kindle Voyage, buying an e-reader has been a complicated process. The Voyage is amazing: high-res, super smooth to use, lots of memory. But it's expensive, and the Kindle Paperwhite is a fantastic device in its own right.
The decision should be a little easier now, because Amazon just announced a new, $119 Paperwhite that includes the best thing about the Voyage: that amazing display. The new Paperwhite has a 300ppi screen---double the pixels of the previous version---which should be just as crisp and sharp as the Voyage. It's still just showing shades of gray, but if the Voyage is any indication, it really does improve the reading experience. And, lest we worry, the Paperwhite's battery life is still absurdly long even with all the extra pixels.
It's not like the Paperwhite's screen was horrid before, of course. This upgrade is for the persnickety reader who whines about the jagged edges of a "z" while sipping red wine and peering through glasses perched atop the tip of their nose. In fact, there are lots of upgrades for that reader. The new Bookerly font, which Amazon designed specifically for reading, is now available on the Paperwhite too. And the Kindle's formatting tools have been overhauled as well, to make the size and spacing feel a little more intentional. You know how sometimes, a line would only have about five words, all spaced way too far apart? That should be gone now.
The goal is to make every size of every typeface feel like it was custom-fit for your device. Small and large fonts have always been hardest to manage, and special attention was paid to those. (Amazon's announcement even includes an entire paragraph on kerning and ligatures, in case you didn't think they were serious about improving this stuff.)
If you already own a Kindle, especially if it's a Paperwhite, there's probably no pressing reason to upgrade. That these features constitute an entirely new version of the Paperwhite is a signal of how mature, and how dominant, the Kindle really is. What's left to solve are the small problems, the nuances and bits of the interface that occasionally remind you that you're not reading a printed book. With custom typefaces, higher-res screens, and automated layout tools that don't feel automated at all, you might start to forget a lot more often.