Interesting. I tested it with sci-fi, and it definitely recommends good books, but not sure how accurate it is at surfacing the sub genres / themes. For example for [aurora -ksr, seveneves, project hail mary, ender's game] it gave me dune. Which is a great book, but not in the "first-ish contact" style I hoped it would be.

Another thing I noticed is that it tends to recommend 2nd and 3rd books in a series, which is a bit so-so. If I add the first book in a series, I probably already read the whole series...