Apple has killed so much convenience over the years; I can remember wanting to buy a Kindle book on my iPhone a decade ago. Crazy that this persisted until today.
Browsing for books on amazon.com is a bit of a pain on a small touch screen. Usually I get out the laptop and use the browser on it. The biggest pain point is when I finish a book and want the next in the series. I'll usually read about one book a day so it gets a bit annoying. I've mostly switched back to my really old Kindle.