Pros
You don't have to work very hard to keep your job. Most people at HQ only perform at a bare minimum effort. You can stay under the radar fairly easily. If you want to work hard you can, but you don't have to do so. The health benefits are very affordable, or at least they were when I was there.
Cons
It doesn't matter how hard you work, if you aren't one of the chosen, you will never get promoted. When I was there, I managed a team in IT, where we were responsible for improving data. Over a period of just over a year, the team improved our area by an increase of 60%. The internal business customers were thrilled. I was thrilled with my team. The team had really risen to the occasion and worked very hard, with measurable results. When it came time for reviews, I gave each team member a very good review, with all the documenation to back it up. When I presented the reviews to my management, I was told I had to rescore everyone at a much lower level. When I asked why, I was told because it made that directors other groups look not as effective as mine. I shared that the other groups were in fact NOT as effective, so they should be rated accordingly. My director yelled at me, saying how dare I compare my team to other people. He forced all the reviews downward, and gave me an average review. He said what the team accomplished was good, but it was what was expected, nothing special. He totally ignored my comment as to why then had the team not accomplished anything in the two years prior to my arrival, and why hadn't other groups performed this 'average' work? He refused to respond, saying only that I was not being a team player.