Downsides are many. Start with that you are working in dog-years. You will work harder then you ever have before. Next the number of not-so-great internal customers and crummy co-workers overbalance that of the good ones. A good size group of people at Amazon are overloaded, working insane hours to just keep ones' head above water. Next there is a much larger group that floats along, doing passable work and maintainig relationships to stay in place. Then there is a small number of "chosen" few, those who benefit from their managers favor with decent hours expected for work and favoritism for advancement. So those doing the majority of work are in the minority.
Another big issue comes up when reviews come around and a single digit percent of the population is to be managed out. This can have to do with performance, but it can also be that your manager just likes someone else better. To bad, but Amazon has to "keep raising the bar." The average employee may get a small increase and a little bit of stock. Those with favor from the boss get a nice batch of RSUs and cash, too, as a bonus (Dont let them tell you theres no cash bonus - its there just for a few). Just remember that if you are getting an offer from Amazon know that they will try to shill you coming in the door and screw you while you are there, So dont take the first offer. Make sure to get as much stock and base as you can because you will not see much of an increase over time, nor much additional stock grants even if you do a great job.
Then there are the managers and mid-level leadership. When I joined Amazon there was a good size population of good, even great, managers. Those who wanted to help those around them succeed. Over time these people have left, only to be replaced by the average Amazon manager. This person does not care about you. He cares about his bonus (see above). He wants his manager to be happy and show the love. You are just a way for him to benefit. This deportment of a manager is not uncommon; its anywhere. Its just that the bad actors have an added fuel of the Amazonian attitude.
The Amazonian attitude is a cocky, I'm-so-much-more-smarter-than-you, obnoxious, the world owes me attitude. Kind of like a smart mouthy kid who takes the ball home when he doesnt get his way. A majority of the managers at place really have this aura, as do many many others. The place reeks of this cocky snarkyness. And you'll be that way, too, if you work there. It creeps in and takes over. You might not know its there until your spouse tells you so. Then again you are smarter then your spouse! Ha! They couldnt get a job at Amazon!! You might not know you have the attitude until after you leave the company. Then its a hangover when you go to your next company. Amazon thrives on a culture of argument. You want to win? Better have good metrics and a stomach for confrontation. If you cannot argue well you will be eaten for lunch. At any and all levels across the company. That attituide doesnt work in the real world where you coorperate with your peers and co-workers, say please and thank you, are polite. Try some of that argumentive agressive manner with yor new company and it will be noticed in a negative light.
And then there is Amazon HR and recruiting. Amazon was at one time a great place to go to work and prove oneself. If you could make it there you showed to the world that you had great skills. Thats no longer the case. The team has grown huge and the bar for competency has dropped. The lower it goes, the more recruiters they hire. And the bar drops again. The chosen few I spoke of above is really the case in HR and recruiting. Sad, but true. Win your managers favor and you'll go far.
In sum my opinion is that Amazon is not a classy company. That venier of friendliness to the outside world hides the crass, boorish behaviors within the company. Want to work there, great! Yes, if you want to you can bring your dog to work, and/or dress like a street person. Just know theres a price to pay for the opportunity.
