Pros
It's refreshing to work for a SaaS startup that manages to be human, and still have a proven and powerful product. Coming from a VC backed firm in the Bay Area I noticed two things right away: The ability for anyone - no matter what their title - to implement a new strategy or idea, and be trusted from the start. This, combined with a transparent culture means that you can spend time helping the company grow, not because you feel like you'll best your colleague, or because it's politically advantageous, but because there's a sense that everyone will grow because of it: Transparent and collaborative, with plenty of potential to grow. Can't ask for more.
Cons
Typical startup woes in the sense that there's plenty of work to be done, and plenty of hats to be worn. You're given the freedom to balance and prioritize, but for some the lack of structure may be difficult.