This is an excellent ebook reader which until recently rightly deserved five stars. Recent updates (starting from about 3 weeks ago) messed up device going to sleep after application exit. This is (obviously) connected to the app's setting controlling whether to force the display to stay on. When this setting is enabled  after exiting from the app the display stays on until the app is forcibly removed from memory (I forcibly stop it via the launcher). My phone uses Android 4.4.2. These problems never occurred until last month.
September 18 2015