Avantages
Organization has prestigious name and history. The humanitarian aid side of things seems to be run very well. On the field work side of things, the IRC has a huge scope of work and provides a lot more services than most other humanitarian agencies. But also many chances to network with other humanitarian agencies. It would probably be a good place to do an internship to get experience for work in the field. For other areas (external outreach, HR etc.) you can probably get a lot of mileage from the name on your resume. Good office location and compensation is about equal to that of similar sized humanitarian agencies.
Inconvénients
As former reviewer posted, be prepared to be over-worked and under-appreciated. Very little personal training and reluctance to invest in employee development in any way. Impossibly high expectations at times for lower and mid-level employees. Very stressful. Very strange dynamics going on here - levels of micromanagement all the way to the top but complete lack of project ownership until something goes well. Blame inevitably trickles down. Many internal struggles between senior staff that make doing ones job very, very difficult. Process for promotions and hiring does not seem fair and organization is generally 'top heavy'. Organization announced a non-essential hiring/promotion freeze less than a week after promoting 6 most senior staff members and a number of employees at employment level. Benefits program is not good - they do not even have maternity leave and coverage by healthcare plan is less than basic.