I worked at AWS. Your experience may vary significantly depending on which team you are in, either at AWS or plain-Amazon. Some people are having the time of their lives there. Some are working horrible hours, maintaining crap old code that they hate, and struggling with performance reviews that saps their morale and prevents them from seeking a better team or leaving the company. Some people genuinely like the competitiveness, the politics, and know the Leadership Principles like it's the law.

Amazon is a fascinating company, it's Big Capitalism in a way no other company is today, and as such it's writing History, for better or worse. For the average developer it's not great, though.