The Opus is small and very light and easy to carry around, in fact easier than a paper back. It "wakes up" and "goes to sleep" with a flick of a button.
You can use fonts you like; you can use lots of different sizes.
Folders (I don't know how people get by without folders).
It reads lots of formats.
It's French and the two CEOs are adorable geeks
who have no idea about public relations
So you would be supporting a small company and free enterprise (love Sony and use their phones, but they don't need the business)
I love mine.