Actually I like the simplicity of Sumatra PDF alot. You can use Sumatra PDF to open any EPUB files. Sumatra is PDF, ePub, MOBI, CHM, XPS, DjVu, CBZ, CBR all in one reader for Windows. Sumatra PDF for Windows can be used to open Epub files:
It is used in Barnes & Noble Nook, Sony Reader, iPhone/iPod Touch (using various e-book apps), and more. EPUB (electronic publication) is a free and open e-book standard by the International Digital Publishing Forum (IDPF) known as EPUB or EPub.
