Pros
I loved working for the IRC for the most part because of its international, dynamic, hardworking, friendly and experienced staff, overall mission, generally good external reputation and growing openness to innovation. I had a national contract and the salary was competitive in the country I was based in, and they often offered internal learning opportunities. With David Miliband at the helm, they're also very good in their external communications and partnership building.
Cons
No benefits as someone with a national contract. On paper, there is an effort to be more innovative from HQ but management on both the country and global levels didn't know how to put this into practice. Like all big humanitarian and development agencies, it's still slow-moving and resistant to change and innovation. At IRC, I unfortunately experienced poor financial planning leading to lack of funding, lack of accountability and responsibility, no desire to understand innovative projects that didn't fit into a traditional humanitarian box on the country level, high turnover at the director level, and generally poor leadership. The country director also made no effort to create a collaborative and sociable work environment in the office. Instead the office energy was often quite low, most of us barely knew each other, we almost never had office-wide staff meetings, didn't know what any other other teams were working on, and HR was also useless and spent time gossiping instead of supporting staff. Of course your experience depends on whether you're in a field office vs. HQ, and each country office is obviously different depending on management.