Pros
Owner has the holy trinity of any start up:
1) a Mission that's real and helps normal people (not just people in tech)
2) rapid growth and financial success -- the fundamentals of the business are very sound, the leadership team is stacked. Founder / CEO is brilliant and human.
3) A pretty strong culture (if a bit uneven in pockets, see below).
If you're an ambitious person who wants to be part of a winning company, feel good about the work you're doing / impact you're having, and like your co-workers, you will thrive at Owner.
Cons
The pace comments mentioned here aren't exaggerating. Only work here if you like working hard. You can have a full life: many successful people at Owner are involved parents or have busy lives outside of work. But they still work very hard. It's one of the reasons the company has been so successful.
One other potential con is uneven-ness in management experience. This is not unique to Owner, any start up that is growing fast and promoting internally faces this issue. What it means is sometimes certain teams or people might have a different cultural experience than Owner's standard. But this should improve as the company matures and develops its leaders more consistently.