What are some alternatives?
calibre - Ebook manager, viewer & converter
Moon Reader - Innovative book reader with powerful controls & full functions
FBReader - FBReader is an e-book reader for various platforms. Features:
Amazon Kindle - Amazon Kindle software lets you read ebooks on your Kindle, iPhone, iPad, PC, Mac, BlackBerry, and...
iBooks - iBooks is an amazing way to download and read books.
Document Viewer - Document Viewer is a highly customizable document viewer for Android. - SufficientlySecure/document-viewer