Avantages
1) Professionalism: I had a good job while looking for other jobs - a luxury, I know: I could afford to be picky. My interview with Amazon Web Services was done at the same time as two other large companies, but Amazon blew me away with their respect for my time, the time they took to get to know me as a candidate, and the quality of questions they asked of me. 2) In a league of their own: The professionalism I saw during the interview process transferred into the workplace. Everyone I have met as come from a highly qualified place and brings to the table serious skills. 3) Work-life balance: In my first half year, I have had a pretty good work-life balance. Things are picking up, but there is still some balance. I don't mind working the extra time as I am well compensated and this is the big leagues.
Inconvénients
Creation out of chaos? It takes a long time to learn who is who at the company, and what org does what. By the time you know the place, it get's reorganized. Other teams may try to do what you do, so you have to be the best. Abstractly, this could yield a very darwinian process where the best teams survive, but organizationally (and from a resources point of view) it seems very inefficient.