Pros
Wonderful, intelligent colleagues. Some opportunities for interesting work even at entry level, some supervisors are thoughtful and encouraging. Travel and professional development are possible. For those passionate about the international development field, you may find much to like. Org seems to be moving in a positive direction under new leadership. The physical office space is quite modern and can be a pleasant environment depending on where you are sitting...
Cons
Turnover and burnout are extremely high at entry level (and later), it is common for new hires to leave after a year. A considerable amount of admin work persists even at program officer level. (These issues vary a lot between divisions and even programs.) Work life balance is so-so. Be prepared to have your duties, supervisor, position or program change at the drop of a hat. Quite hierarchical and traditional in many ways (again depending on program) - a "this is how it's always done" mentality.