I recently downloaded an $8 epub version of Lee Child's latest bestseller to my iPhone. I'm using the free iStanza reader app to read it (they let you customize the whole reading experience). It's sharp, clear, and the book is so good the rapid finger swiping to page through is quickly forgotten. I always have this smartphone with me so I always have this book. The only problem is, unlike a physical book, it's easy to forget I actually have it. Too much other stuff coming at me on the device.
As an author, I'm concerned about the future of long-form reading, ie, books.