Sounds like yes, the PDF wasn't formatted with the hard stops, AND your Sony Reader's software has good text reflow ability. Without either one of those two, PDF is a nightmare on e-book readers. Epub, on the other hand, is a standard e-book format designed for e-book readers. Don't get me wrong, I'm glad there's PDF versions too! But not every PDF works well on my e-book reader, so I'm glad I can create epubs.
