A beautiful new look and feel
Skim through multiple pages easily and quickly—just touch any page to enter Skim mode
See your bookmarks and thumbnails of pages in the book’s progress bar
See footnotes without leaving your current page
In-book search remembers your previous searches and groups results by chapter
Simple management of downloaded content

This release does not have a Play Store Description, so we grabbed one from version 3.15.5:

Make digital reading even easier with Google Play Books, featuring smart recommendations personalized just for you, access to millions of best sellers, comics, and textbooks, and loads of customizable features.

Just some of the highlights of Play Books are:

* Preview free samples from our catalog of millions of books including romance, comics, mystery, sci-fi, young adult & more
* Read your books, comics, and textbooks on Android, iOS, or your web browser, even when you’re offline
* Find your next read via our highly personalized recommendations, curated series and author pages, and in-app alerts about new releases you’ll love
* Read Discover, a daily feed of book news & stories with articles from Slate, Vox, the Google Play editors, and more (US only)
* Follow your favorite comics series, devour our weekly deals, and read about your favorite superhero with Bubble Zoom, an exclusive technology preview that’s available on select titles
* Customize your reading experience by choosing your preferred font, text size, or page color, and make late night reading easier on your eyes with Night Light
* Rent or buy digital textbooks and study better when you harness the power of Google with integrated Google Search, rapid Skim Mode, Quick Bookmarks, and the ability to easily sync your notes and highlights to Google Drive