Fantastic challenges, great craic, excellent people
Pros
Despite having several thousand employees, you can still have an impact, and it doesn't have to be "wrote the messaging system", it can be as simple as "made something more efficient, saving hundreds of thousands of dollars over a year", or "enabling someone else to be a rock star". There are great challenges in the infrastructure, and it's a first-hand experience of (at the heart) simple systems interacting in complex ways. Lovely food from the on-campus cafe (really and truly I'd call it a restaurant, the food is that good), break out areas for peace and quiet, and generally excellent and smart co-workers.
Cons
Long days mostly, and the communication lag with HQ. It's possible to get sucked down a rabbit hole for days on end, sinking in far too many hours. However, in the end, it's a personal choice to do hours and hours of work beyond what you're salaried for. The 8 hour lag with California is also a pain in the rear - you either live with 24 hour turnaround on question/answer threads, or you stay late to try and catch someone in real time.
