As a bibliophile I LOVE the concept of this game. It's also extremely difficult -- which I also love. :)
However, there were several books in my pools that I wasn't familiar with, so they felt kind of wasted. I like text interfaces but I think there's an opportunity in the UI here to eventually also let players "inspect" the books they're working with (seeing a summary or synopsis would be very helpful!). In this case, I think the text interface got in the way a little bit, although typing "2 5" wasn't too bad, it did seem like I would have preferred to see all my books on a shelf / on a surface / etc and just be able to drag them onto each other to combine them. However, I appreciate that the text interface did force me to slow down and think through my combinations more, which doesn't often happen in combination games.
It'd also be really interesting to be able to see a history of combinations of books. I combined The Iliad and Paradise Lost into The Waste Land (which I wasn't familiar with), and forgot that's how I got that -- it would have been nice to be able to see that those two books previously combined into this one, but it's also be really interesting to just be able to browse all kinds of books and see the combinations of other books that make them up -- I'd just be curious what classics would combine into some of my other favorite books!