Pros
Giant aspirations for changing the world combined with a high likelihood of achieving them. Executing on a vast number of initiatives simultaneously, and succeeding. The employee benefits are excellent, the compensation competitive, and the opportunities for movement within the organization is incredibly high; very little friction to following your passion somewhere else within the org.
Cons
The organization has grown quickly and there are pockets of people who are reluctant to change and progress with the company. There is quite a distribution of work ethic across the org, and an unfortunate sense of entitlement in a portion of people. These are the same issues that I've experienced at every company; they're just universal truths of companies that grow.