Pros
Vacation and benefit packages far exceed the norm in the United States. Every staff member, regardless of rank or tenure, receives 30 paid vacation days per year plus holidays. The only limitation is that you cannot stockpile and carry more than 60 days from one year to the next. But, seriously, if you can be away from the office for 3 months, which is more irrelevant: your job or you? Additionally, the pension system is first rate: 100% match after 10 years of service. Also not to be underestimated is the education and awareness you receive by working with and learning about the cultures of people from over 190 countries. If you are a non-US citizen (or if you are a US Citizen posted abroad), you will receive a very generous education grant for your children (until they reach the age of 25 or complete their first degree - whichever comes first)
Cons
The snail's pace and red tape rampant in all bureaucracies, croneyism and the fact that mediocrity is frequently preferred over meritocracy. Because of mandated quotas, geographical concerns can sometimes trump merit as well. Also not uncommon is finding loud and troublesome colleagues - who intimidate afraid-to-take-a-stand-and-deal-with-what-will-be-non-stop letters of appeal managers - receiving glowing performance evaluations and faster than normal promotions. Some of the fastest ways to get promoted are to never rock the boat and always demur rather than decide.