While the company puts customers first, the same isn't done for employees.
Burdensome operationally. You'll have a pager rotation which varies from awful to not too bad (other than you need to be able to log in at all times). Tons of overhead tasks like hardware planning, permissions audits, monitoring etc. These take a substantial amount of time and are about as uninteresting as it gets in engineering.
Annual review process is political, confrontational and even hostile. Everyone is stack ranked. This is common in the industry but Amazon takes it to a new level. Other managers in your division are motivated to push you down the ranking scale to get their own employees higher up. They have incentive to trash you in the ranking meetings so you have to watch your back. There's high manager turnover so if you have a manager who is inexperienced at this process, you're at risk of being downgraded which happens quite often. They don't care much because they'll just higher many more brand new engineers. Nobody seems to care that the company is overwhelmingly staffed by relatively inexperienced engineers. If you're not, you're expected to mentor more and more of them and if you don't do that well, you will get a poor review.
Promotions are extremely difficult. Other than from SDE I to SDE II, it's quite difficult to get promoted. I know many top notch engineers that have remained at the same level for 5-10 years.
People do get promoted and many deserve this but there's an art to it. You have to be fortunate enough to have a champion there who is willing to sponsor you and support you and do an incredible amount of documentation proving why you deserve it. They'll also need to rebut inevitable arguments against your promotion by other managers (see above). Lots of the time the promotion won't happen. It's not explicitly quota based but that's how it works out.
Obviously I have mixed feelings about Amazon. Ipet
