One possible use is quickly finishing a book that started out promising but is proving somewhat disappointing. I hate to abandon a book, and I'll only do so if it feels like a complete waste of time. But I would have been happy, for instance, to step on the gas about halfway through The Luminaries, which won both the Governor General's Award and the Man Booker Prize last year. What began as an intriguing tale of murder and mystery set during the 1860s New Zealand gold rush, packed with lots of well-defined characters, was not ultimately very fulfilling, in my opinion. Satisfying endings are not terribly common, but in this case, I found myself caring less and less about the characters as the story dragged on. With a really good novel, the opposite happens.
If this technology pans out, I'll have more time to spend with higher quality books, which is reason enough to be excited. But as the cost of reading (in terms of time) falls, simple economics suggests that most people will probably read more, which frankly would be great. Just think: A wiser, more knowledgeable, more empathetic world may be right around the corner.