There is single large window displaying text, with lots of space between the lines. At the top, there are tabs with the names of different books. It looks like

There is single large window displaying text, with lots of space between the lines. At the top, there are tabs with the names of different books. It looks like you can scroll in the large window displaying text to read a book. Also at the top, there are dropdown menus with what I assume are different application options. At the bottom, there is a sliding position indicator labeled "Document position". It looks the way I would expect an older e-book reader application to look. It seems totally usable and intuitive. I know exactly where to click and what I might expect to happen. There could definitely be some aesthetic improvements, but as far as "UI functionality" is concerned, this is great.