Pros
Very nonstressful, librarians are always willing to chat and help, will have tasks that differ based on which branch you work at. I work in a research division and this will often include tasks like sorting books, cataloguing material, setting up apointments. I have a manager that is very flexible about hours and when I could come in, as well as time off -- as this is a position only for students that makes sense, you could work shifts as small as 3 hours throughout the week before cap at 19 hours. You also get a staff discount at the NYPl shop for 10-30% off, and access to NYPL events and staff events.
Cons
Very repetitive, will often leave you time where you are just waiting at a desk or standing around for a task or for a patron that might need assistance. Lunchs are not paid, and the expected amount of hours is 19 with more time having to be requested to your manager.