Pros
Everyone can agree that the Bill & Melinda Gates Foundation does world changing work. I have worked there in two different capacities two different times in the last 9 years and the culture of highly competitive, extremely intelligent people remain. The company still operates as a young organization in that it embraces new ideas and it's always evolving. People who dislike change would not be happy here. The benefits can't be beat and the environment is stunning in the new campus. They encourage working from home and remote work, which is helpful in the sometimes intense and stressful office environment.
Cons
This is a company of academics, there is not a lot of silliness or fun happening at this organization, which makes sense due to the importance of their mission. There is a competitive feeling throughout the company that can feel oppressive, but they still embrance a sense of creativity and change. They constantly re-org often with little to no notice or reasoning behind the changes which is pretty jarring, so you have to be someone who can embrance change easily to thrive in this environment.