jmc8501, thanks for the feedback. Some questions:
- What do you mean by "unstable" scrolling?
- Are there specific places where the reader feels laggy?

The idea behind Katana is that it's "infinite-scroll" - i.e. you can scroll forever. Having to stop at the end of a book doesn't fit in with that, and I'm planning to remove that limitation. So, with infinite scroll, scrollbars don't really make sense.

You can actually use the volume rocker to page up/down. This is especially nice in portrait mode, because you can hold the phone in your right hand and your thumb falls right on the rocker. That's the way that I use Katana 90% of the time.

Hope that helps!