The chaotic lean environment. On the pro side it leaves loads of room for opportunity to make a difference, which is possible. Just when you think you've made a difference by performing 15 different tasks to accomplish a goal (10 of which were not really yours to do, but you did them because there was no one else to pick it up), everything shifts in frequent re-orgs. Resources are lost, roadmaps change dramatically, documentation is poor to non-existent, which causes lost momentum that sucks the life out of you.
The lack of processes and routines. This is not true for 100% of the company, but is for many areas that one would think a company of 10+ years would have nailed. The constant reorganization of teams and leaders breaks any continuity that was established prior to the reorg. I was dumbfounded when I learned that a certain team in the company had absolutely no idea of the steps it took to issue a payment to a supplier. I think they thought it was all black magic. Project processes were another area that some key development teams made up as they went and changed quarterly. This created loads of knee-jerk reactions for many teams impacted across the company and challenged goodwill with internal relationships.
HR could care less about employees. Loads of lip service from the HR teams to make you think they care. Like many other groups in the company, their individual teams don't seem to talk to one another, or know each other for that matter. It is as if each team has blinders on and they only know and perform only their function in strict confines. There is lots of "that's not my job" attitudes. As an example, I witnessed on more than one occasion where great performers took international assignments only to return to leave the company because the company did nothing to help reintegrate the employees. What I heard is that HR managers and recruiters did nothing to assist these employees returning from their assignments, each one saying it was not their job. It was left to the employee to figure it out themselves. So after the company spends tens of thousands of dollars to move staff around the world yet the company expects nothing in return? How dumb is that?
Below market pay. Amazon is known for paying below market in terms of base salary yet expects people to work at least 50 hours per week. Many teams due to them being lean require 60+ hours a week. HR sells the entire compensation package with stock which can be great in a up market and if you live in the US. The odd thing is the mixed message they send with it: the stock makes you an owner of the company but because they call it comp, they expect you to sell each time you vest. I would rather have a larger base pay.
Amazon is no different than other companies in that it has it's own dysfunctions. If you have an iron will and a high tolerance for stress, you will do well there. Use the company as much as it uses you and it will be a happy relationship.