Pros
I am thoroughly impressed with the quality of my colleagues. They are competent, they care about doing excellent work, and they treat each other well. I look forward to seeing my team every day. Some of the benefits are incredible, such as the $10 allotment for fertility/adoption each year, and the full medical coverage w/o employee contribution. Finally, in areas where there is room for improvement, you quickly find that there are plenty of outspoken allies already pushing for change.
Cons
There are certainly growing pains with such a quickly-expanding company. "Move Fast" is a company mantra that is often given too much leeway to cause chaos to downstream systems and teams. A slightly slower pace of growth and change would make for happier employees and a more sustainable model.