After looking very carefully at all of the specs and capabilities of the Amazon Kindle ebook reader... I went out on Friday and bought the Sony ebook reader. So far I am cautiously happy with it. Both devices have serious limitations and are very over-priced. However the Sony reader handles pdfs adequately well rather than using a format that may become obsolete (Amazon seems to be already phasing out the fairly successful but proprietary Mobi-format).
I am already getting more reading done because the reader is easy to carry around and use at different times during the day. So, you may see a few more reviews from me now :)