Recently, I bought a Sony PRS-505 ebook reader. After using it for a few days, I generally like it. Because of my eye sight, I read in medium font in landscape mode. All the reading I have done are pdf files. I can use it under direct sunlight - which is good.
Apart from the default "s" mode (which can stand for standard or small), medium and large fonts are available. However, these later modes are a re-flow of the pdf text. It did not work for a Chinese pdf I was reading. I have not tested on other Chinese pdf yet.
Some of my pdf has a fairly large white margin, if there is a magnifier mode so that I can fill the screen with text and push the margin outside, I would be able to read the pdf without using re-flow.
However there are a few improvements that may make it better.
1. Non-reflective coating of the screen will help in situation where is a high contrast of light and shadow.
2. The processor performance should improve. Yes, the screen refresh is slow compared to other display technology, it does not hence imply a low performing processor. I generally find switching pages in medium or large font mode too slow possibly due to the need of re-flowing.
3. A different magnification mode may also be useful. (see above)
4. A larger display area would certainly help. Given it is an ebook reader, I suppose the target market would be people like me, ie old enough to still read books, have some eye sight issues (need reading glasses all the time). A small screen is certainly no good.
5. My reader come with a leather jacket. I find that I cannot fold the cover back and hence I need one hand to keep the cover open, very ignoring.