Interesting for texts at work, informational texts and such things. Lyric and entertaining fiction I would prefer in the old format: not even e-readers, but printed on paper.
http://www.springwise.com/read-300-p...0-minutes-app/
I could imagine that it becomes exhausting to the brain and stressful to the eye after some time when reading very long texts that way -
right because you do not move the eyes, do not easily interrupt for a short brake, and always "stare".