Pros
You immediately start working on projects that are impactful to the company. It is an amazingly supportive and collaborative work environment. Being a smaller company, each employee gets a lot of opportunities to work on projects that they may not have had exposure to in a larger company. From ping pong tournaments to happy hours, the company culture is fantastic. It is a company full of very smart people who are driven and really care about doing good work.
Cons
It is a pretty good problem to have, but with growing so rapidly, there are times when the workload can be a little overwhelming. The up-side to that is that everyone is willing to lend a hand. The company is still young and building infrastructure, which means that you get to participate in that, but also that sometimes things can feel chaotic.