Pros
It's a great place to learn how the world works. This involves both learning about how a large international bureaucracy manages itself, as well as learning about governance in developing nations. While the Bank as made some mistakes in the past, it is really a place where you can make a positive impact on the world. NO INCOME TAXES! Foreign employees in the DC office are exempt from US income taxes, and the Bank pays state and local income taxes for domestic employees.
Cons
It is really hard to get a job at the World Bank. Don't take it too hard if you are rejected. Above a certain threshold, it is almost random who gets jobs and who does not. There are a lot of politics: personal, organizational, and sometimes ever geo-political. This can be stimulating if you like that sort of thing, but those who are not politically savy will struggle.