Pros
The people at Mercy Corps are top-notch, passionate, committed, and brilliant. Whether they be national or expatriate, the quality of the programmatic and technical thinking is high, and the culture at Mercy Corps promotes adaptive human-centered design/programming.
Cons
Mercy Corps makes it difficult to operationalize strategy, and they're less effective for it. Whereas the technical thinking is excellent, in my experience, things fall apart when the rubber hits the road. The systems for supporting operations and management are poor, with little support in carrying over lessons learned and best practices from previous programs. Every program seems to be left to reinvent the wheel when developing management systems, impacting the degree to which teams can carry out the program management cycle effectively.