As part of Google updating everything last night they updated the Play Books app. Not only have Google updated the interface to be in-line with the other Google Play apps they have also added some new features.
What’s in this version:
Support for reading your own PDF or EPUB files. You can upload the files through our website play.google.com/books/uploads, and read them on all your devices.
Refreshed design including the library, Table Of Contents view and the recommendation page at the end of books.
A confirmation dialog to prevent you from accidentally un-downloading a book.
Stability and performance improvements.
Play Store Link – Play Books