Pros
The work/life balance is rather good here. Some roles require a little bit of on-call work, but this is balanced out across the team pretty well, and otherwise work stays at work. Even when a crisis would occur, I saw mainly constructive interactions between workers. The environment is pretty relaxed and laid back.
Cons
As others have noted, the culture is still pretty much in start-up mode, which means that internal standards and documentation are pretty much non-existent. Project direction is still subject to change at a moment's notice, and there are many half-completed systems and partially implemented features throughout the released product. Day-to-day focus is usually on implementing the newest shiny, or on fixing whatever crisis has shown up due to the tangled code base. Tech debt is pretty extensive here. This company doesn't really seem to invest much in its employees. They do have "leadership seminars" for their management-level people, but I don't think training for anyone else was ever mentioned as an option. Similarly, while they are growing their numbers right now, all upward mobility seems to be confined to the core group others have described. The gap is made up with new hires; which means for any non-core employee, the most you can do to advance your career within the company is a lateral shift to entry level in another department. Pay and benefits have been described by the company president as "in line with industry standards". While not much of a con by itself, I think this emphasizes the lack of investment this company has in its people - they'll do enough that they don't really lose many employees, but they don't really work to attract and retain the best people, or to help their people become the best.