It looks like it has the same physical form factor as last year's Kindle
Paperwhite, but has a higher contrast E Ink display, a faster processor
for improved page turning and book opening, and a redesigned built-in
light. The touchscreen has also been improved, which should make for an
improved page-turning experience.
The improved processor does the
job, making the device feel much faster and more fluid than ever
before, and the screen is the best we've seen on a Kindle. The light is
brighter than before and the improved contrast makes it a superior
option compared to the older model.
Overall navigation has been
improved, as well — you can preview pages before actually turning to
them, which makes looking up an index or map much easier. And the
improved X-Ray tool does a much better job at defining words in the
context of what you're reading. There's also a nifty Vocabulary Builder
tool, which collects the words you've looked up; you can go back through
them, or even create flashcards to teach yourself once and for all what
"etymology" really means.