Pros
Tremendous opportunity to grow and learn if you're willing. The company hires good talent in all teams so you'll always find a subject matter expert about a question you have. Management team is intense and demanding, which you want in early stage. On the flip side, they work hard and lead by example, and they'll make time to talk to you if you ask. Big focus on culture as the company grows, which is very appreciated. Overall, good communication between teams through meetings and collaborative projects, so it's easy to learn what others do at the company. At their core, everyone is a good person and bought in on the same mission.
Cons
Not for the faint of heart in terms of pace and standards, but that's been the case in every successful startup I've worked at. Still figuring out certain internal processes but you can view that as an opportunity to define them yourself.