OK, it's an ipod touch, not a smartphone but I read on it a lot. I've always read on small screens BET* so size is not a problem. In fact, because its small size and is always with me, the ipod gets used more for reading than any of my other devices. (to quote many a *ahem* more modest size male "It's not how big it is that matters, It's how often you use it"
)
* before eink and tablets
P.S. It's not a mackerel, it's a flounder. They are flatter and keep the rain and snow off better.