Veja abaixo a lista oficial de melhorias presentes nesta versão (em inglês):
Improved Font: We've improved the reading font to have more contrast and be more crisp.
Parental Controls: With the latest software update for Kindle Keyboard, parents can restrict access to the Experimental Web Browser, the Kindle Store, and Archived Items. While the Kindle Store and Archived Items are locked with Parental Controls, you can continue to buy books from a computer and send them to the Kindle wirelessly for a child to read.
Kindle Format 8: KF8 makes books look even better with support for author specified fonts and more book styling options.
Comic Books: Kindle Keyboard now supports comic books with Kindle Panel View. Supported titles can be purchased from the Kindle Store. Books open in Kindle Panel View by default (a view that allows you to read a comic book panel by panel).
Children's Picture Books: Kindle Keyboard supports children's picture books with Kindle Text Pop-Up. Supported titles can be purchased from the Kindle Store.
Whispersync for Voice: Now you can switch back and forth between reading and listening without losing your place. Whispersync for Voice will synchronize what you read on any Kindle platform device with Audible playback on Kindle Keyboard, Kindle Fire, or on Audible apps for iPhone and Android.
Para mais detalhes e saber como atualizar seu Kindle consulte a página oficial.