[Dr. Drib]

To answer the question you pose in your thread title: No, this doesn't interest me whatsoever, and I would never use it.

Covers interest me a lot more than spines - (re: calibre). Covers (for books) only interest me in bookcases. In fact, I will sometimes put the cover facing out, to give 'color' to the bookcase display. I will often take the book out of the bookcase, turn it this way and that way, open it, read a few pages here or there, relish the smell of the pages, etc.

For ebooks, I could care less about seeing a spine and would never use this app, let alone download it.