Simultaneously the best and worst experience
Pros
The positive impact that the company is having all over the world is outstanding even if the company doesn't share this externally. There are many professional development opportunities to allow you keep growing. The perks could be a pro like free food, laundry, salon, etc. but I personally found it to feel like the company wants to keep you there instead of going home and having social interactions with people outside of Facebook. But, if you don' t have a strong social support network, it's a great set up. My co-workers were by far the best part of the company!
Cons
The hiring process is very strange as they hire people without knowing what team they'll be on, allowing for an opportunity to be placed on a team that's not a great fit, and then being stuck in it and not being able to move around until at least a year in. HR seems most concerned about protecting the company rather than really listening to employees and their concerns. There is a lot of turnover lately...I had 4 managers in about a 9 month span, which leads to really confusing situations. They also keep bad managers in their positions, even if there have been multiple concerns raised about them from a whole team. The values the company promotes are great in theory, but I don't see them in practice.