I have a Kindle and bought quite a few books on it, but I didn't like being 'owned' by Amazon and beholden to them forever more.
I tried Kobo, but had a few problems which their support department were hopeless about. They didn't answer the questions they just sent out standard template mails that answered some other question.
So yesterday, when I was just about to buy another book from Amazon, I did a search for the book title +epub and found it immediately on smashwords.com.
The price was reasonable, and I had a choice of about a dozen formats.
I downloade as an epub and was reading it on my Playbook straight away.
But the great thing is I now have the epub forever, and so I'm not tied to Amazon or anyone else for that matter. I'm free.
I read the first book yesterday and bought another today and I wasn't even on wifi. I was tethered to my Blackberry phone and was amazed at how fast it downloaded.
Problem is, now you are "owned" by smashwords.com instead of amazon or kobo.
No, because you download the file in the format you want and you have it forever more. You're not tied to smashwords at all. The choice of formats for the two books I got were everything from epub to pdf.
Hopefully, more and more authors will look at making their books available from these places and that way both readers and authors won't be beholden to Amazon forevermore.