Pros
Smart people. Cutting edge technologies. Amazing food.
Cons
Some huge, out-of-control egos in management, especially at the middle layers. Couple that with the general immaturity of the company and you'll see some very poor judgement and "Game of Thrones" style politics in a few departments. Average tenure of a staff engineer is about 4 years - mostly because after the initial stock grants vest there is near zero incentive for anyone under a Director level to stay any longer. Culture creates and fosters entitled whiners - so much so that it is a running joke inside the company, with groups such as "Patently Absurd Requests for Facebook Offices" making fun of it all. But then again, this company is largely made up of the "participation trophy" generation, who have been told they were super-special since they were born. Being hired by Facebook amplifies that self-esteem level well beyond eleven. It is never spoken about, but staff turnover is huge. The washout rate of n00bs is likely around 40%. Truly talented staff move around, so team continuity is rare. Zero work-life balance - unless you happen to have a kid while working there.
