Pros
Fast paced and energetic environment. You're given a lot of responsibility, regardless of level, and really get to have a chance to have an impact on the business. It's easy to move around the company and even make large career changes. There's no workplace politics that can prevent you from finding a new team or taking your career/promotions into your own hand. With plenty open roles and teams across the world, there's really an opportunity for everyone at Amazon to find something that they truly enjoy. It's also a really fun work environment, with a young workforce. I really enjoy the open learning sessions you can join to learn about what other teams are working on, there's plenty of company/team sponsored events, relaxed work environment where you can enjoy a drink with coworkers while you relax at your desk in the afternoon. Flexible work life balance is really appreciated.
Cons
You definitely will work hard, feel dumb a fair amount of time, and need to have or develop quickly a back bone. At times it seems tough, but when I look back at how much I learned at Amazon in only a couple years compared to previous companies, my knowledge has grown tenfold and I'm incredibly happy I took the opportunity to join Amazon. And again, if you feel that the team you're on isn't a good fit or the role that you're in isn't quite working out for you, switch. It's that easy.