Pros
Coworkers and supervisors all have a great attitude. It made it fun and enjoyable to work there. Supervisors trust their employees to know their jobs and do them, so there's no micro-management. If you have a question about your work, even a stupid one, nobody judges you for asking. They prefer to hire up from the inside, and with constant turnover, there's always a new position opening up above you that's worth applying to.
Cons
Like most libraries, they don't pay well enough to make a career out of it unless you're at the top. There was constant turnover. A recent round of promotions included some screwy business that ended with disagreements among managers and several people leaving. Hard to know if what went on was entirely ethical, as nobody from management talked about what happened.