Pros
You get to work directly with the co-founders in most cases. Loved learning from them about their ideas and things to come. Everyone is open to suggestions and welcome expert feedback. Everyone keeps communication lines open, no matter how busy. No usage of corporate lingo and keeps feedback clear, open and honest. They recommed working in a way that benefits your sleep, emotional health and social life.
Cons
Everyone in the team is upfront about where you stand, especially anyone you report to. Which means that you'll know where you stand with any given project. They communicate it clearly and don't bury it under weird language or communication tactics. If you're not a fan of direct feedback about what your superiors like and don't like, you won't like it here. Projects move along quickly because of this fundamental philosophy. Wasn't a con for me but may be a con for others who don't appreciate the direct approach.