Pros
You definitely feel empowered in a way that's expected in a startup. The people you work with are also incredibly fun and their energy and ambition is inspiring. Though there are walls and tons of unnecessary red tape, there is real desire to be as transparent as possible. (Not saying it's fully transparent, but the attempt is really appreciated)
Cons
I have very little faith in the HR department. The management team is essentially uneffective. This is redundant in many of the reviews you read, but they either promote untrained employees into strategic and managerial roles, or worse, they don't provide support for some of the most influential and experienced managers and they are let go or forced to leave. Second, veterans of the company are starting to leave in droves. This isn't a good sign, and it weakens morale. Third, this company has so much red tape. I don't know why, but I feel like I'm in a corporate maze (wihtout the amazing 401k and the six-figure salary). Lastly, I think the company is now struggling to see what makes them enticing for an IPO or what they can possibly sell (if it is looking to sell).