The app contains exactly what you'd expect from an official app from JW, and members will definitely love it. The app's interface lets you mark pages as favorites and turn pages by swiping your finger on the screen, too.
Other features that will make your life easier are the history and search. The first one lets you come back to any previous reading, while the second lets you quickly find anything you're interested in.
JW Library is an application aimed mainly at Jehovah's Witnesses, who are sure to love both the content and the interface, which is really polished.