Pros
Facebook decided somewhere along the line that speed and engineer efficiency mattered more than predictability and avoiding mistakes. The result is a rather refreshing environment where engineers are expected to take risks and use our discretion to jump on what we see as most important. My co-workers are amazing - facebook's been able to hire some of the best talent in the valley and it shows. The perks are top tier. It's just gratifying to work for a company with a sense of mission about creating good in the world, and that's at Facebook's heart. It's certainly helpful to love using the product yourself - but as long as you derive satisfaction from the billion people who do, you'll be happy working here.
Cons
Suspecting facebook of nefarious motives is a popular if misguided silicon valley pastime. Usually trying to argue people out of it is a waste of your time. :/
