Pros
The experience you can gain is incredible. You will be thrown into things you are under qualified for. If you can survive it is a great resume builder. You really do feel like your work will help change the world.
Cons
Pay is a joke. We try and pay like a startup, i.e. significantly below market rate(50%-75%) with equity incentives. 4 years ago that still made sense, but with where the stock is today you do not have a chance to hit the "startup lottery". Hours can be rough and most departments are understaffed. The employees they do have are often under qualified. Constant fighting between groups; it is often a giant game of CYA instead of fixing problems(more so than any company I've worked at before). Lack of proper systems. If excel disappeared the company would shut down.