Pros
Great camaraderie between workers when you have to pull together. Especially when it's amongst people you get on with. Good benefits: good pension; free shares; chance to Save/Buy As You Earn in the form of more shares at reduced price; make additional contributions to you pension pot, etc, etc. To be honest, I loved the day to day work. It was simple and straightforward and I really enjoy dealing with public (most of the time). But there were certainly problems...
Cons
Advancement can be difficult to break into, despite company posters and literature laying about all over the place claiming the contrary. People getting promoted who're considered completely inappropriate by managers and staff alike. Staff booking time off for weddings, holidays, and family childbirth a year ahead, only to be told just a couple weeks before hand they'll need to rearrange everything. Holidays needing to be booked 18-months ahead!