Pros
People are quite kind and typically motivated by the mission. Most are genuinely trying to do their job and make an impact on whatever problem they're solving. Nice employee perks beyond standard benefits (e.g. sabbatical after 5 years, anniversary stipends, etc.). Comp for my role (non-technical) was higher than market, though I know comp for other functions can be quite below market. Actually a great place to work if you are a lower-ranking IC (non-CX) or are father removed from the center of it all.
Cons
Unclear whether the company has an actual overall market strategy it is executing against because exec decision making takes so long / shifts often, and planning is almost entirely bottoms up. Being the first mover / dominant player in category means there's so much opportunity to go after that leadership can't focus (FOMO). Additionally, tons of growing pains operationally that have never been solved along the way -- expected more maturity for a company of the size and age, still feels Series B. None of the above is insurmountable but can feel that way as there is little productive recognition of these issues on the part of mid-to-senior management. Culture is friendly, but tends to minimize issues and lots of social pressure to wrap any constructive feedback in so much positivity that it dilutes the impact or urgency of the issue itself. Frequent turnover at the executive / senior manager levels which is destabilizing for ICs / roadmap continuity.