Pros
If you're in high school, shelving is a great job. You can put your headphones in, have a calm 4-hour shift, and feel satisfied that the building is more organized than when you came in. Very little interaction with patrons, so this is not a customer service job where you will get yelled at. Opportunity to take on extra hours if you want to.
Cons
If you're out of school trying to make a living, and your partner doesn't work or you're single, the library is probably not for you. Circulation ladies and librarians tend to have some weird interactions with patrons, but that's really not specific to this library. Getting time off work can be stressful as shelvers have to switch shifts with other shelvers, and it's not always easy to find someone to cover, especially around holidays. Some management could use training on how to manage people.