Pros
Company has funds for new technology and processes. Most of the employees are professional and hard working, however some (including managers) are petty. This is no different from other large organizations. Benefits are great even with phase out of pension for new employees. 401K has excellent match. Medical is great. Salaries are average for non-managers. Working conditions are excellent at my site.
Cons
Unless you are anointed, advancement can be very slow. Factors other than merit guide assignments to challenging work. Most people are little cogs in a big organizational machine. Processes and methods are very company specific and may not be transferable. Unless you are in St of Washington, need to be able to move for advancement.