Pros
The organization has quadrupled in size since I came, and has brought in great talent in IT, business/finance, sales, govt affairs, marketing, customer service, HR, etc. Also more reliance now on smart mid-level managers to provide leadership, instead of just a few people at the top. They can now compete with the big guys, and rely less on consultants. Good news is that they have managed to sustain a culture of cooperation and genuinely nice, helpful colleagues. You will have all the responsibility you can handle, opportunities to present new ideas, and there are no slackers - come with your A game. Fun stuff like happy hours, birthday parties, company-wide events. Beautiful office.
Cons
Mission-driven non-profit means no equity/stock for employees. But good salaries and benefits mostly make up for that. Too many meetings.