FB has some of the best people working on solving extremely complex problems that impact everyone around the world. Having the opportunity to be a part of that is incredible. You get great mentors, interesting projects, amazing offices and perks, and a performance culture that can really help you improve your skills.
Cons
Working for a global company can be challenging in terms of work-life balance. There are at any given time of the day thousands of people working, and that can create a need to be online and contribute.