Pros
Large organisation with plenty of scope to move around in to different roles - if you are lucky. Decent benefits nothing brilliant. Good company pension scheme. A good company to move in to if you are coming in at senior management level.
Cons
Poor salaries compared to other organisations. Pay bands and gradings make little sense and are very political. Some managers seem to know nothing about the area and teams they are managing. Some employees have tunnel vision and can't see anything outside of the areas they are focused on. HR seem too be clueless at times and very cold. Far to many layers of management, too much politics and bureaucracy at the organisation so takes a millenium to get anything actually done. Far too behind competitors in terms of technology being used at the company and this will never change due to the fact people are reluctant to try new things and due to politics. If you come in from an aquisition chances are you could be stuck in a role you don't want and not see a decent pay rise for a considerable amount of time. Senior management completely out of touch with the rest of the organisation.