Pros
You'll be working with some of the smartest, most able, most passionate people you'll ever meet. You'll get opportunities to succeed (and fail) beyond your abilities or scope and if you're good, you'll get a lot of responsibility fast (though maybe not the title, salary or recognition that responsibility deserves). You'll work on projects, programs, innovations that touch millions of customers worldwide. Rarely will you work for a company whose customers feel so passionate about the service - and tell you about it too. If you're data-driven, have good judgment, like to build things and like to move quickly, Amazon will be a great place for you. And you'll have great stories when you go to parties (except of course, they're all business confidential).
Kontras
The hours (like the rumors of Microsoft only more so - especially during Holiday Season). The lack of employee recognition (the downside to constantly looking for ways to improve something is you often forget to stop & acknowledge work well done). The salary. People (distant cousins at Thanksgiving, acquaintances at parties) asking you to help expedite their problem order (only partly joking here - of course it happens).