In my case, the most competitive UI in desktop e-reader

It does look pretty and it's probably very usable on a tablet, but on a full-featured computer (i.e. one equipped with keyboard and mouse) it's inefficient and idiotic.

Your comment is overly hostile. The author is present, you could give some constructive feedback instead of insulting the design.

I actually disagree with you, the UI seems elegant and very usable on desktop. Maybe smallish window size on screenshots give impression that it's more suitable for tablet?

Ok, idiotic was not the right word. I apologise.