Pros
You are working for a mission driven organization and most likely some of what you do is going to make a difference. There are some people that actually care about the work tho and not about their status and how it looks for them to work there.
Cons
If you are not a white savior (google articles in guardian- this has been documented about IRC) you probably won't be treated fairly. Found this to be true while I was there a few years ago, a friend started to work there who is black and couldn't believe the racial discrimination at the HQ, and left. It's also full of people who were in the top consulting companies who are trying to relieve their white guilt, so expect that consulting culture. During Black Lives Matter, they talked the talked but no action other than folks realizing how inequitable it was and leaving including the person they hired for DEI (again google this).