So I really like and appreciate the EPUB format for e-books for a number of reasons.

One it holds out the hope for becoming the standard format for e-books. For a former web site designer who recalls too well the efforts of Microsoft and Netscape to develop there custom version of HTML, JS, and DOM, and the contorted code that was required to design pages that would look and behave the same in both browsers, the advantages of a universal e-book format seem obvious. Of course the big if for there ever being one format, or at least one overwhelmingly predominate format, is whether or not the big ugly gorilla in the room (aka Amazon) will want to keep a separate format for their e-books and Kindle.

Another reason is that editing an EPUB version book is something almost anyone can do. I know that a lot of people here with Sony devices still prefer LRF files, but personally I always convert even these to EPUBs. Once in that file format anyone with a program to decompress the file (and who doesn't have one of these) and enough basic knowledge of HTML and CSS can reformat the the book however they please.

Reason three is that when the formatting is done with the proper use of CSS, thus achieving the intent of XML—separate content from formatting—it is easy to take the actual content and reformat it at will.