It's simply a souped-up version of the previous generation Paperwhite that launched last year. All your favorite features and capabilities are here – no glare in sunlight, fast page turns, and take notes in your digital margins.
As far as what brand-new features you can look forward to here, there's a Vocabulary Builder that will maintain a list of new words you learn as your read. Tap a footnote to instantly bring it up in-line. There's no new page to load.
There's Goodreads integration on the way, which ought to add a really cool social layer to the Kindle user experience as people share reading lists and chat about what they've read. (Amazon bought Goodreads, a social network that lets you share what you're reading, in March.)
The entry-level model (which displays those "special features" advertisements when not in use) costs $119. If advertising repulses you, there's an ad-free model for $139.