My dad usually reads a book per day, so we don't haul this many books with us. He used the library a lot when we were on the Ryndam. If you are not too choosy and have a wide variety of tastes, you can use this to supplement what you take with you.
There is a spot in the library for passengers to swap their read paperbacks for those other passengers have left. Sometimes the selection here is great. I always leave mine when I'm through with them....makes for a lighter suitcase on the way home!