Pros
Depends on your manager and department, but some departments have great flexibility. Also the benefits are pretty good, although health care benefits are declining. Plus as one long-time employee who does very little work told me "this place is great because you can hide".
Cons
The old fashion bureaucratic system of having 8 to 14 levels of managers above the people actually doing the work, means that there are layers and layers of folks just getting paid to tell the next level above them, what the folks below them are doing. Plus none of these managers has the guts to make the slackers actually work, since they themselves want to be slackers. There are tons of people taking 2-hours lunches, talking on their phones, playing on the internet, coming in late, leaving early, pretending to be sick, but nothing is ever done about it.