Pros
A lot of opportunities to build and look at solving problems in unique ways in comparison to what you'll normally find in Silicon Valley along with really great work/life balance. This largely stems from quick growth while trying to figure out what it means to successfully bring together diverse employees cutting across technology and philanthropy backgrounds. If you're interested in figuring out how to build an organization through these challenges, then you'll find it rewarding and you'll be pushed to grow yourself tremendously.
Cons
It's unclear how to successfully weave two very different cultures and backgrounds together which causes organizational challenges on a day to day basis. If you don't enjoy working somewhere which is rapidly evolving, requires nuance to succeed, and forgiveness along the way, then you'll find it quite frustrating.