I'm not a usability expert although I certainly have read a bunch and seen a bunch of presentations (and know a few experts personally), but there are some basic ideas about understanding your user and the tasks they have to perform with your app or device or site that should be somewhat obvious.
I often read books and articles on my iPhone while nursing/rocking my babies. Maybe it makes me a bad mother but it sure has helped with patience over the past almost 18 months! If they're awake and up to shenanigans, I put the phone away and give them my full attention... but anyway. People are shocked and amazed that I can put up with reading a book on my iPhone. I'm not sure why - it's not a tiny font, I can make the font whatever size I need. I have the phone with me anyway. I don't need a separate light source. I can get new books right there instead of having to connect it to my laptop.
One of the things that is super, super important for an immersive reading experience is the ability to quickly turn pages - without even thinking about it and without losing your train of thought. When you're reading on a small screen, you might have like 4 page turns to every one you would have with a print book so it's something you do a lot. (particularly if you're reading <ahem> trashy bodice ripper romances <ahem> that read very quickly!)
Overdrive is the only app you're supposed to be able to use with the Overdrive license my local publib has. They have made two major mistakes with page turning - it's like they don't really get it? First, a while ago they added automation when you turn a page. So it would look like the corner turning up and going over - what a colossally bad idea! No one turns pages because it's cool - you turn pages to see what happens next. They quickly reversed that and made it an option. In the most recent update they've added a bunch of cool things like synching across platforms (good), but they've now made it a swipe instead of a tap to turn the page... and you can't even swipe from the side because that opens a menu, you have to swipe in the middle... which is hard to do one-handed while holding the device. And it's slow... it has to think about it before turning. So then you have to go back and check what was happening and then go forward again... I had a book on there that I had had on hold for a while and I just gave up on it. I'm going back to reading about Web Corpus Construction in a pdf reader like Good Reader.
Update: This afternoon Overdrive released a new version that fixes the page turning issue. I can only hope that they learned from it this time when they didn't learn from it last time.