Pros
Really smart and dedicated people. You will learn quickly how to craft your ideas and explain them to others. You will be challenged.
Cons
Expect to invest 100% of yourself into this job. There is no time for anything else. I enjoyed my work here, but burned out after about a year and a half. I worked nights, weekends, whatever was "necessary". If you haven't read the New york Times article "Inside Amazon: Wrestling Big Ideas in a Bruising Workplace" read it. I lived this everyday. I left on good terms and have been asked to come back several times, but have declined after talking with current employees and seeing that the conditions have not changed from when I was an employee. Additional notes: Decisions never get made on time by management. Everything is micromanaged.