Here is what the update site says:
Hide Reading Progress Option
While reading, tap the bottom left of the screen to switch between four reading progress options, including Location in book, Time left in chapter, Time left in book, and None, which hides your reading progress from the bottom of the screen. To learn more, go to View Your Reading Progress.
Optimized PDF Performance
Increased stability for complex PDF files and shorter time to open documents.
Improved Homonym Lookup in Chinese and Japanese
When you look up a word that has multiple meanings for the same spelling (homonym), you can view a full list of the available definitions from within the dictionary definition window.
It is available at
update cite.