Pros
Facebook in general is a great company to work for. All the amazing perks you read about in all the other reviews, leadership does give off the impression that they care about their employees. Everyone is very smart and in most cases people are enthusiastic about collaborating and conversing about new ideas. You will learn a lot very quickly and often be inspired by the ideas and leadership of others.
Cons
Outside of Facebook probably being responsible for destroying the moral fabric of society, Your experience at Facebook is highly dependent on your manager and team. That said, stay away from Research Operations. I have never seen such poor, uninspiring, thoughtless leadership in my career. Multiple ICs have had to take extended leave because they could not take the abuse from management and were broken down to the point where they felt they had no value. Managers are reported to HR repeatedly, without any action taken. Leadership on that team would rather defend managers to the death than support an IC. There are at least two similar reviews on Glassdoor about this team.