Looks like a very nice ebook reader. Could probably replace Calibre for 90% of users. It's already on the Arch platform so here are my thoughts on using it for 5 minutes. Rendering is via poppler which is fine most of the time but definitely not as fast as mupdf + zathura when testing a epub textbook. Definitely has some bugs (clicking on links to different parts of the book don't work for me) but it's still in early development so that's expected. Reading regular books is pretty good but there should be a preset to center text with large margins on the sides (like an article) so it's more readable fullscreen. Definitely has potential but will be sticking to zathura for now.