Pros
(Duty Station: HQ) you get to meet some of the best, most dedicated experts in the world who have worked on key health issues for the vulnerable. You also get to see the “realpolitik” of global health here. As long as you hold a staff contract, salary can be quite good. Also, lots of free time on your hands to study or have a family.
Cons
Too bureaucratic, leading to the agency becoming more and more irrelevant, especially in comparison to UNICEF, UNHCR, etc. It’s an old boys’ club, and it’s difficult to suggest any new ideas nor do any meaningful work if you are junior-mid level staff, because there will be so much outsourcing that you’ll mostly be left with contract management. Funding situation is pretty bad too, which translates to job insecurity.