Pros
Amazon does a great job of hiring the best people. You will get to work with some of the smartest people you'll encounter anywhere. I met more people with 2+ advanced degrees while working in the supply chain group than anywhere else.
Cons
There is hardly any chance of a person receiving a promotion. Part of the problem with hiring the best people is that really good performance is considered average. With hundreds of engineers in an organization only a tiny number would ever be promoted in a year. It's very discouraging. There are 2 very different worlds in Amazon, the older areas and the newer ones. Working in the original operations or retail areas you can have a work life balance. However, in the AWS division people are expected to work roughly 60 hours per week. There is no work/life balance. If you have a family your spouse really can't have a job.