First and foremost, Amazon is boasting that they've improved support for magazines with glossy, full-color layouts. The app also has better support for navigating inside a PDF; now you are offered a thumbnail preview (I thought the app already had that). The textbook improvements include a new notebook for your annotations (note, highlights, bookmarks, and ritual incantations for a better grade). Students can now also highlight images and add the images to a note.
• Bug fixes and performance improvements.
• Enjoy your favorite magazines with glossy, full-color layouts, photographs and illustrations.
• Easier PDF navigation with visual previews of each page.
Improvements for textbooks:
• Highlights, bookmarks and notes are organized into a notebook.
• Textbooks now support highlighting pictures.
It's been a couple months since the last update, which added the damned carousel view and prettified the menus. That wasn't much of a change, not compared to today's update.
By offering students a notebook for their folders, Amazon is moving into direct competition with dedicated digital textbook platforms like Kno, Coursesmart, Inkling, and the like. Amazon might not be able to offer textbooks dripping with fancy moving illustrations (unlike the 3 I mentioned), but Amazon does offer support for more platforms and a better selection of non-textbook titles.
I still haven't seen any sign that digital textbooks are being adopted in droves, but Amazon is clearly laying the groundwork for the day that happens.