Pros
Very transparent company culture with a big emphasis on cross disciplinary collaboration, which in practice means I always have a lot of context, know what's going on the company, and have more ability to grow my career/skill set by figuring out what types of problems we will need to solve in the future and taking initiative to move in that direction early. Surprisingly good work-life balance for a startup. Plus, of course it's exciting that I have stock options in a company that is clearly going places!
Cons
Really tough to think of cons, but I would say that if my biggest motivation were pure cash compensation, I could probably get a little more elsewhere. High volume of hiring has made it a little bit tough to book conference rooms at the moment (although we are looking to move to a larger office soon).