Unfortunately, though I respect Amazon a great deal, I don't think Bezos has any idea what really happens on the floor of his fulfillment centers. So here's a breakdown:
Moral: The atmosphere has become extremely negative. We used to be encouraged to talk to our co-workers while on the floor (as long as we stayed productive), because it was good for morale. As morale was boosted, so was productivity. Now, the attitude is if you're talking, you're not working hard enough. If we don't keep our head down, eyes front, and mouths closed, we get "coached" about work ethic. We also used to be encouraged to give feedback to our managers. Managers called it an "open door policy." After all, there is no better expert of a particular process than the people doing it all day. That philosophy worked, too. But that changed. Now everything's micromanaged by middle management, and any feedback, no matter how constructive, is treated like an attitude problem.
Workload: At first glance, the work doesn't seem hard. But that's deceptive. Labor hours have been reduced to a skeleton crew. Few people in certain roles are pushed past their physical limit, resulting in injuries. And if you get hurt on the job, they report it as a non work related injury, even though it isn't. Thus, not only are you disqualified from Workman's Comp, but they can also fire you, and keep saying on record how safe they are.
Pay: They say competitive pay, but they don't tell you that they're comparing you with general retail jobs such as JCPenny, Sears, and Wal-Mart, although it's a warehouse job. They don't compare our pay to other warehouse jobs or distribution centers (ie. Meijer Distribution, CostCo, etc.) because they're all union jobs with excellent pay.
Opportunity for growth: If you aren't a military officer, there is no opportunity for growth. There is one promotion you can earn, after that, that's it. Area managers and above are hired from outside, usually from the military, and anyone applying for a promotion are told they're not qualified, in spite of their degrees, years of experience, and expertise of the process. They tell you what you need, only to move the goal post the next time you apply.
Work-life balance: There is none. It's that simple. I come home from a ten (sometimes twelve) hour shift too tired to eat dinner. That's not an exaggeration. My daily life is: get up, go to work, come home, pass out on top of my covers on my bed with my clothes still on. Sometimes, I have to settle for the couch, as the stairs prove too much of an obstacle. That's not a rant; my roommate made fun of me about that the other day.
All in all, after five years there, I'm pretty miserable. It's a good short term job, especially during the holiday season, but don't make a career out of it.