Pros
The mission is certainly compelling, to be part of something that noble is truly motivating. In my country, the pay is way above market (salaries are at least 1.5 times higher than what you can get in the private sector). Work-life balance was also good at the location where I was (GSSC). Health insurance is also way better than what our country offers. Inclusion and diversity (in terms of gender, religion, sexual orientation) is the best an organization can get.
Cons
Very bureaucratic and hierarchy-based culture (even when common sense or fairness are not what the rules say, the organization favors the rules and the hierarchy above everything else). Although the organization is very inclusive when it comes to "standard" stereotypes (gender, religion, sexual orientation), there is a non-sense distinction between the "locals" and the "internationals". There is a clear difference, in a meeting you cannot be right if an international says something else than you, they are always right, same with the hierarchy: you cannot know something better than your boss, in their mind, it is just impossible. Felt like whenever we were asked about anything, it was always just for the "show", just so they could write in a report or present somewhere that they did ask. Leadership is poor, and there are decisions that do not make sense, selections for assignments and promotions are almost always depend on who you're friends with.
