Pros
Amazon hires very smart, reasonable people. While people are A-types, people are cooperative and willing to work toward the greater good -- customers. That said, it is _very_ customer focused with a very strong corporate culture. The technologies available to work on are world-class, albeit it can take time to learn it all as much of it is steeped in tribal knowledge.
Cons
Work-life balance is tenuous at best. Even in relaxed areas, the only way to get ahead is to put in a lot of over-time. Some areas talk of 40-hour weeks, this is what it takes to just stay afloat. This can lead to lone warriors pushing changes to team code. A lot of agile team de-evolve into ad-hoc processes. A lot of work is geared toward maintenance engineering than cutting-edge engineering; the challenge is to remain stimulated. Operational support can vary from team to team, in some instances being on-call is minimal; in others it can drown you.