Pros
A wonderful place to work with smart, friendly, helpful people all focused on a truly meaningful mission. It feels great to know we are making a real difference in our members lives. There is so much upside in the product. It works well, now, but there is so much room for improvement, and os much ability to have a big impact the product. The company is at a perfect size, small enough that you can know everyone, and work fairly fluidly, but big enough to know it's for real and have the resources to do stuff Very transparent culture, good work/life balance, considering it's a wildly ambitious start-up. Everyone wants to ship good product and get stuff done.
Cons
So far, so good. If you are jerk, you won't like it here. This is a start-up, and like all start-ups you need to push for what you believe is right, and not expect everything to to be smooth.