-Working in a company where mission and vision are first, where the mission and vision matter in this world.
-Flat org structure
-Consistently testing your comfort zone, receiving the opportunity to try new things and implement new ideas.
Cons
I've worked full-time for 3 companies and as an intern for 5 companies. Facebook is the best company for which I have ever worked. Like any company it isn't perfect, but we carefully choose the ways in which we are not perfect.