So why I had found it easier to read from my iPhone? First, an ordinary page of text is split into about four pages. The spacing seems generous and because of this I don't get lost on the page. Second, the handset's brightness makes it easier to take in words. "Many dyslexics have problems with 'crowding', where they're distracted by the words surrounding the word they're trying to read," says John Stein, Professor of Neuroscience at Oxford University and chair of the Dyslexia Research Trust. "When reading text on a small phone, you're reducing the crowding effect."I have felt exactly the same way (perhaps I'm a bit dyslexic myself but never realized it). Additionally, I can make the words as large or as small as I want, and I can bust out a few screens between Metro stops without losing my spot.
In the world of printed books, bigger fonts equals more pages, which increases printing costs and makes the book more cumbersome to hold, carry, and fit onto a bookshelf. So the trend was to use the smallest font possible that could still be legible to most people, while jamming the pages full of text.
No such printing cost restraints exist for the delivery of an e-book, so I suspect readers will start to prefer larger fonts. Of course, frequently flipping through screens can be annoying too, but e-bookers are now free to optimize the experience however they see fit.