Pros
I came to Amazon 9 years ago and learned a lot. I was continuously challenged and pushed in the cold, Darwinian way that Amazon loves so much. This helped me get exposure to processes and technology that I wouldn't have had in a smaller company. It enforced a discipline that has benefitted me since then.
Cons
Amazon is a Darwinian environment. You hit the ground running and if you don't keep up your life will be miserable. This inherently is biased toward single, ambitious type-A personalities who live off of Bezos's words and happily spend 60+ hours a week in meetings, projects, meetings about projects, meetings about long-term plans about projects, traveling to remote sites, etc. The amount of "heroics" that I and my fellow engineers had to do to keep things running and maintain and "average" review rating was not trivial and looking back it was not always worth it. The humiliation and pressure from management to keep up and get promoted gave me a lot of anxiety and stress-related illnesses that were not worth it in the long-run. If you decide to work for Amazon you should go in with the thought that you will only stay long enough to gain valuable experience, improve your skills, and then get out. I made the mistake of staying too long hoping things would get better. They won't. Also, as a final warning, expect a large portion of your compensation to come from RSUs which come twice a year. If you don't budget wisely, you can be in a world of financial hurt even at Amazon's pay scale.