I use it for keeping track of the books I have and the ones I read, and also my opinions about them.

The recommendations by the site are useless to me, and the opinions of other readers are more hit than miss. Often the most voted ones are full of emoticons and memes, or do not say anything useful about the book but are upvoted because the reviewer is popular or something. A lot of reviewers have not even read the book, and are mad at the writer because of some Twitter controversy or things like that.

Lists are also extremely useless, same as the newsletter.