Move fast, have fun, make an impact -- proud to work here
Pros
The company culture is open, friendly, fast, fun -- and competitive, in the best way possible. I've never worked in an environment where people are so ready to pitch in, work together, and praise others for a job well done, while at the same time constructive and pointed feedback is encouraged, accepted, and acted upon. Yes, the perks are excellent -- free food and snacks, great benefits, etc. But it's the environment and culture, and the caliber of people we hire (technical and non-technical alike) that make it such an incredible place to work. Work-life balance is tough anywhere, but I come from a job where you were on 24 hours a day, 7 days a week, and vacations were rare (and managers certainly didn't encourage you to take them). Here it's the opposite. We work a lot but managers tend to be cognizant of burnout, and actively encourage folks to spend more time outside of the office, be with our families, and take time for ourselves.
Cons
Because things move so quickly, and it's such an open environment, there is occasionally needless duplication of work. But while frustrating, it's incredibly rare.