Pros
Working for something that brings more meaning to the world other than just profits and numbers. I think it's hugely satisfying to be in a team that cares about its mission. As a designer at Causecast, I had huge opportunities to take on challenges I'd never done and to work with an amazing pool of talent. The average age of the employees here range from mid-20s to mid-30s, which makes for a pretty relaxed and fun atmosphere. Lunch is provided on Mondays and Wednesdays, and there is a quarterly office-wide volunteer day. The pay is competitive, and benefits are pretty nice--we get every bank holiday off. They do beer/cocktails on Fridays. Everyone is respectful and collaborative. The work-life balance is pretty incredible.
Cons
It's a start-up, and it's ramping up as such, so there are some growing pains, but I think this is to be expected from any start-up company.