On the Windows desktop app (possibly also Mac version, but I don't know), there is a weakness in Paged View (1-column or more) that I'd never noticed before I tried to actually read a book cover to cover in this mode. You can't tell how far you are through the book because there is no scroll bar in this view (by design).
There needs to be some progress indicator in lieu of a scroll bar, to show what page out of N pages (if the book is paginated), or what percentage through the book you are. For example, maybe if you hover the mouse over one of the paging arrows, it would pop up this info, so that it doesn't take up any permanent screen real estate. Or else maybe show it on the empty space of the Locator Bar if that is visible.
