This is great. One piece of feedback, maybe make the objective or goal larger or more prominent. I failed the first couple because I wasn't quite sure what my objective was and didn't notice it right away.
I wonder if you could incorporate bonus points in some way by using details from the books? So it someone is a really voracious reader, they could answer questions or have some incentive for reading the books displayed? This could also be great for kids or young readers.