Pros
I was in Amazon Web Services on the EC2 team so this may or may not be relevant to Amazon as a whole. Anyway, you're surrounded by smart, capable people, which is great, and you're working on products that a lot of businesses are going to use.
Cons
Because of Amazon's ruthless policies, your co-workers are your enemies, not your friends. You're all fighting not to be the among the bottom-ranked in your team or department, and thus you must constantly be concerned about making yourself look good and your co-workers look bad. Friendships are a liability, though alliances may not. Also for that purpose, visibility is important. It's not sufficient to do your job and know your stuff; you have to make everyone aware of it. Don't be the invisible one in the back toiling away getting no recognition; that gets you fired. Below 50 hours a week and you're in the firing crosshairs. The internal saying is "If you want work-life balance, you don't love your job enough". Amazon deliberately understaffs, partly in the belief that the sheer pressure will drive innovation. You have to be aggressive in making sure other people are prominently and visibly blamed when you can't get stuff done.