Avantages
Amazon has invested a lot in the development infrastructure. There are a lot of tools in place to make writing and deploying code easier; the learning curve can be steep but they really do focus on getting developers to a place where they are adding value. The team you work on will really impact how much you work and how intense your on-call is but my team has very reasonable expectations. I never work more than 40 hours a week and our on-call is very mild. This is not true for all teams.
Inconvénients
The focus on "Bias for Action" sometimes equates to the ends justify the means and you get people who basically think they can bully you into doing what they want. Your experience at Amazon will really vary based on your team but can be hard to predict in advance.