It doesn't work for me personally... not to say it won't for others.
First off, I have to pay for a device, then pay again for the book. A book I don't really own, I just have the right to read it, and not resell or lend it. Quasi lend....OK sure.
I like to read when on a plane. i.e. Lite stuff by Randy Wayne White, I find used for cheap. $0.50 - $2.99
I just looked on Amazon and Ebooks and the cheapest they have is $5.99 and up and they only have around five or six books, out of the 30+ he has written.
The Cloud - What was once old is new again.
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I remember the days of, "Hey is the server down again?"... "S**t, I was just about to save too."
Now we can sound all trendy and ask, "Is the cloud is down?" and complain about how slow file recovery is.

So far for me..... it's just an electronic device to help separate people from their money.