What are some alternatives?
FBReader - FBReader is an e-book reader for various platforms. Features:
Moon Reader - Innovative book reader with powerful controls & full functions
Cool Reader - Fast and small cross-platform eBook reader for desktops and handheld devices
Document Viewer - Document Viewer is a highly customizable document viewer for Android. - SufficientlySecure/document-viewer
Google Play Books - Google Play Books lets you search, preview, and buy millions of books using Google Book Search.
iBooks - iBooks is an amazing way to download and read books.