Pros
Scale -- Amazing opportunity to have exposure to large-scale ecommerce, website, infrastructure. Truly the most top-notch security folks I have seen anywhere. Solid Company -- I believe that Amazon has a good, solid core business and that Jeff truly does have vision. Amazing colleagues -- Some really smart, good people that I have loved to work with. Exceedingly competent software development overall. Vacation -- stay there long enough (7+ years) and you'll get a decent amount of vacation.
Cons
Compensation -- get the best comp package you can when you start, because you won't get much thereafter and everything will be based on that. If you luck out with a good manager that will fight for you, you may have a chance. Otherwise, the only way to get any decent raises is to get really well known and a lot of senior management to think on you favorably (without making any enemies) so that when your name comes up in a ratings review meeting. Reviews -- feedback/actual performance and compensation are unrelated. Promotions are fights requiring significant documentation and a boss that likes you and a boss that likes your boss. Management is generally very hit or miss -- a good manager can make all the difference in the world and a bad manager can be only mildly damaging at best. Employee recognition (especially for non-software developers) is nonexistent unless your particular manager cares about it. As with many larger companies, the individual group you are in makes a huge difference.