Its generally large file sizes can use up precious storage and processing power in
mobile devices; and it's limited in its ability to «reflow» to suit
different screen sizes (anywhere from a couple of
dozen to 100 or more characters wide), an important issue in the ebook world where the same ebook might be viewed on a large computer screen or a small
mobile phone screen.
Each book's page comes with a dropdown menu of
dozens of
different file formats, anything from a zip file to a PDF file to a format suitable for most any
mobile device out on the market today.