Not everyone who reads .PDF files on their reader buys them. Some of us use our reader to read things we are sent for work purposes, and they get sent to us in .PDF format, and we don't have a choice. We're not necessarily assuming that it's the best format. It's just all we've got. It's worthwhile to know exactly what the limitations and challenges are in reading .PDFs on our devices, but just being told not to isn't very helpful, I have to agree.
The .PDF format forum here contains a lot of tools for modifying .PDFs to make them easier (if not easy) to read on mobile devices -- and I think the Sony works decently well, or at least as well as can be expected. It's the reason I chose a Sony over a Kindle, personally.
And yes, Sony's software for the 505 works on Vista (which is what I usually use), and yes, it supports reflow -- though, as noted, the line breaks on a .PDF don't usually line up with paragraphs so it might look a little funny. (Personally, however, it doesn't bother me that much if a line breaks at
a funny spot so long as I
can read it.
)