I have posted the following on the blog at my ebook store. I would welcome comments.
The introduction of the Kindle has created a heightened interest in ebooks. While there have been a number of different ebook readers available for a number of years, the Kindle seems to have captured the attention of a great number of people who hadn't considered ebooks in the past. While I believe this attention is good for ebooks in general, I believe that for educational ebooks PDF is the best format for overall use. I have put together 10 reasons why I believe this to be true.
In brief, the reasons are: comfort, equipment, cost, fonts, pictures, layout, external links, internal links, printing, and cross platform capabilities.
Entire post on ebooks in education and PDF
Thanks,
Kevin