Pros
Facebook is a top tech company like Google, LinkedIn, Apple and many others. All of these companies offer basically the same thing: great engineers, good money, free food, impacting zillions of people and interesting tech problems. Facebook has a few things that set it apart: 1. Open-ness. Root on every box, access to every source repo. I very rarely had to wait to receive credentials to do anything. At other jobs you're often blocked sitting at your desk for a few days waiting for access to some repository. 2. Control over your career. You don't get hired into a specific team -- you choose it (in recent years they've added a list of teams you can choose from, but there's still a lot of variety). And if you get bored or feel stalled, you're encouraged to switch teams. I don't think other companies offer those things. The real list of pros is huge, but since they could be applied to other companies I don't include them here. The only reason I left is because I always wanted to start my own startup. Otherwise I would have stayed forever.
Cons
With everyone switching teams all the time there is often a lot of lost tribal knowledge. So there's parts of the codebase that no one understands anymore. Since the Great Shift to Mobile there's been a focus on quality at the expense of moving fast. I really liked the Move Fast and Break Things mentality of Facebook when I joined, and though people disagree with me, I prefer it to the "don't ship it until it's perfect" mentality (I think many of the independent Facebook apps waited too long to launch). Another thing that no one will agree with me on is the work-life balance. I have noticed a trend of people working less, hackathons running during the day, etc. I think your average employee is less driven and moves slower than a few years ago. This used to be a place where people were obsessed with shipping above all else. It isn't that anymore. This is a pro for some people but not for me. I'm giving it a 5 because I think it's good for your life, not because I agree with that balance.
