I have made the observation that reading e-books on my Motorola Droid has the same advantages as playing mobile games on the device. I recently wrote an article explaining why the PSP phone will fail and reading books on a mobile device parallels the same advantages as well a developed mobile game.
Games on mobile need to be easy to quickly engage and disengage from, thus games with a complex levels and long load times fail to become accessible when time is limited. This is why I believe it's better to keep console games away from the handheld market. It turns out that like an entertaining mobile game, e-readers allow for a quick flip through a book.
One of my good friends recommended a book to me one Saturday and I didn't want to make the trip out to Barnes & Noble so I decided to give it a shot downloading the book from the Amazon Kindle app on my Droid. I'm a very slow reader but to my surprise I almost finished this book in a week. What I realized was I didn't have to wait for that perfect opportunity to sit down and read to a "good stopping point." Whenever I had a minute or two I was able to pull out my phone and read through as far as time would allow without feeling that I was committing myself to a long read.
Now that I feel comfortable reading books on my phone I will visit the bookstore even less.