I tried downloading a 'full' version of a reader app from a random site once, and my phone started getting pop-up ads every five minutes until I did a factory reset.

: The safest way to download iReader is through the Google Play Store.

: Apps downloaded outside official stores do not receive automatic security patches or bug fixes, leaving your device vulnerable to exploits . Authenticity Check

It's better to use the free version from the Play Store or pay for the VIP; these 'latest' APKs are usually just old versions wrapped in trackers.

: The ability to sync your reading progress across multiple devices. Community Perspectives

: Options for adjusting font size, brightness, and background themes.