Pros
Awesome people, incredibly positive and supportive CEO [rare!], genuine desire to listen to concerns and [usually] make improvements, massive potential for learning cutting-edge tech across the stack, great opportunities for working with and traveling too other offices around the world. Many skilled and passionate people creatively accelerating an emerging market to the next level, with unrelenting focus on the customer journey.
Cons
Top-heavy org with some entrenched operatives and thinking. Pathologically difficult time delegating authority and empowering the proper people. Company has suffered serious attrition of talented mid-level leaders from this one self-inflicting problem. Desire to appear flat has lead to a very small handful of engineering-minded people bottle-necking the decision-making process, churning implementations that don't actually reflect business needs or focus.