Pros
The day to day flexibility is pretty fantastic with credit hours and comp time that allow you to take time off instead of using your regular vacation time. If you play your cards right, you can end up saving up a lot of your regular vacation time which is a nice plus that virtually no other private employer may have. Continuing education programs are top notch with opportunities to work on a job-related graduate courses after work or even during work hours in some cases. There are a lot of offices/groups which allows for bouncing around to different offices when you get bored with where you are. The work-life balance is pretty superb if you play your cards right when it comes to vacation time like I mentioned. Depending on the group you work in, you may have opportunities for paid overtime.
Cons
The environment is a little suffocating sometimes, especially for a young and technical person. A lot of "government" mentality is present -- a lot of people stick to strict schedules and are unwilling to put in an extra few hours to get something done. The inundation of forms, paperwork, performance reviews, etc. often puts a damper on real progress. Most management is very old school and doesn't quite "get" how to manage or "deal with" the younger generations, so there's a clash of ranks once in awhile. Upward mobility can be tough to achieve sometimes because more often than not management waits for someone to retire until their replacement is promoted to fill their place.