Pros
The only reason to work here is that it will improve your future prospects of getting a better job elsewhere. Recruiters know that Amazon has a high hiring bar and employees are motivated to leave. In rare cases and for rare individuals, you will have the opportunity to build something awesome; for everyone else, it is duct tape and bailing wire to survive Christmas.
Cons
If you can work somewhere else, you most likely should. To start with, the work environment is soul crushing and more stressful than working in an airport terminal. The noise level is so great that you will need to wear headphones throughout the day. I worked in buildings which were so overcrowded that you often had to wait for three elevators to find one you could squeeze onto. I am sure that they were in violation of the fire code. For scientists, you will drain your human capital and have little opportunity to learn new skills or deepen your knowledge. Don't even ask about getting Amazon to pay for journal subscription -- you are expected to scrounge papers from friends still in academia or off the Internet. The "mentors" I had were largely useless and it is virtually impossible to earn a promotion without superhuman efforts, i.e., having no work-live balance. In addition, there is a culture of micromanagement which comes down from the top. This attitude makes it difficult to research and to solve important problems which are costing the company millions. And, this is not limited to a single manger -- I had five in two years, all of whom were worse than any manager I had in my 25-year career prior to Amazon. When you attempt to make changes, it can take six months or more of politicking and fighting the Agile/scrum schedule to launch your improvement into production. Amazon takes the leadership principles seriously, but "Deliver Results" and "Bias for Action" trump everything, even correctness. No one seems to remember who made $50MM mistakes, but they do remember who didn't deliver the XYZ feature on time by giving up endless evenings and weekends. Next, read the fine print on everything you sign. Amazon has many pernicious ways of clawing back money from you when you leave, e.g., you must stay two years to avoid repaying relocation expenses and you will only receive matching contributions to your 401(k) if you stay three years. In addition, the infrastructure is "frugal" and often unreliable. If you work in retail and need to run a query in Q4, it can take a day or more to run. Finally, when the market turns against Amazon -- and it will -- the stock will take a major haircut because of the insane P/E ratio.