Pros
Large organization. Good amentities. Cafetaria, gym, and so on. Nice coffee :) Opportunities arise to advance. Or you can twiddle your thumbs and do nothing.
Cons
Highly political. Senior Managers seemed to be focussed on protecting their backs. Knives were out. As a results, rather disorganized. Things can change in an instance. I saw a division closed and people laid off within days. Atmosphere became toxic. A lot of people I worked with were also doing something else e.g. writing a book so that were not that into what they were doing. I was contract. Others who were permanent barely worked at all. I had to pick up the slack for some very lazy people. They took boondoggling to new heights. It was like working for government only the people were better dressed.