Pros
I enjoyed the opportunity to travel. The organization's culture in theory was very open and interesting. SPARK did give me access to entrepreneurs, who inspired me to start my own business without involvement of any NGOs.
Cons
Working for Spark for just under 2 years left me realizing that the organization existed just for the glorification (and financial benefits) of its founder. The projects themselves were completely irrelevant and often of poor quality. In effect, SPARK serves as middle man between the Dutch donors (mainly the government) and local NGOs, taking its sizable cut of the funding in return for reporting and marketing. The upper management was interested only in acquisition of new projects to cover increasing overhead. The modern office culture gave the impression that feedback was welcome but in reality no one spoke up due to legitimate fear of being sidelined.
Rules were applied arbitrarily. For instance, we had to pay local taxes in the developing countries where we worked, but I quickly discovered I was the only one doing so!
When I informed my boss of my intention to quit, I was told I wasn't entrepreneurial enough for the organization. I immediately went on to start several successful businesses.