I started a thread a while back along these lines which drew a lot of similar comment:
https://www.mobileread.com/forums/showthread.php?t=18521
Back then I only owned the Kindle. Now that I have the 505, it is obvious that it is better made and better designed than the Kindle.
Bottom line, however, is that Kindle is marketed by a bookseller and not just any bookseller, the largest bookseller and the one with the greatest popularity online.
So having an electronic reader closely tied and integrated to a bookseller gives Amazon a huge advantage which Sony can never, ever have.
Sony makes electronic devices, they have very little experience selling books, and none of the clout with publishers that Amazon has.
So when the smoke clears in a few years, I suspect the market will mature and Kindle will be a large part of that market.
As I discussed in the old thread, when a market matures and Sony has not dominated, or at least played a major part in it's genesis......they tend to pull out.
Bottom line is..Sony is in the business of making money. If the ebook market proves to be less than profitable they will pull out, history has shown this over and over. Nothing against Sony, just good business sense.