Funnily enough, recently we started a bookclub in our office and we are using slack. Not sure if we need the app, but we might try it.

The biggest challenge for me is to accept when the team chooses an obviously bad book, but they will learn with experience. A feature about book details sounds good but depends on the source and if it is marketing or a good critical one. Finding the book in print would be a nice feature which is easy for english and big countries, but might be hard otherwise.

Edit: maybe consider a feature for setups where people rotate to choose the book if there is not one yet.