Gooner, the Kindles are bespoke to Amazon, but they are better than sony in this regard. The £149 kindle has FREE (well paid for by Amazon with no contract ever) worldwide 3G access. My mate who has one was able to download newspapers and books from the beach in Egypt and send emails to me FOC using the google mail function.
The screen on the kindle is much better than an ipad for lots of reading. There are also lots of free/cheap books available on Kindle.
I am not a massive book reader, so think I would get better use out of an ipad or macbook air, but if I was buying then it would be the £149 kindle.
There are also ways of getting hacked/torrented books onto the kindle. I don’t know how to do that though.