Pros
It's stable. Once employed, if you do your work it is highly unlikely that you will be fired. Everyone is friendly. It's a relaxed and relatively non-competitive company to work in and for. The benefits package is excellent--which I did not appreciate until I left-Particularly the retirement package. You don't realize it until after that they have essentially helped force you to save for retirement so it puts you at a long term advantage.
Cons
There are few opportunities for clear growth. Professional development is not adequately supported or even understood. Direct communication is often not done--so if someone is doing bad frequently the manager will complain to everyone EXCEPT the person in question. Ridiculous. I worked on 6 different projects and saw it happen over and over again. It's a very subversive culture and unproductive.