Pros
The environment is a very fast-paced, get things done no matter what quality you can deliver. The people are very smart and for the most part everyone has some business sense to them (whether you aspire for this or not). There are some really cool projects (e.g. AWS), but they are saved for people who are Amazon veterans (i.e. don't think you'll come into Amazon and work on a cool project right away, unless of course you know someone). The overall compensation is definitely above average (assuming the stock isn't plummeting) but you have to be willing to sacrifice your personal life.
Cons
Amazon is a very frugal company (they still use doors for their desks, the facilities are very blah, no free sodas, they do not donate any money to charities or the arts like MS, Boeing, Washington Mutual, Starbucks do, etc.) that has very high expectations of their employees, including sacrificing your life side of work/life balance. Getting in 50 hours a week was a luxury week, the average is more around 60 hours. The majority of the technical side of the company are SDE's, with proportionately very little QA or PM staffing. This means that organization and quality are not part of deliverables, and leaves room for a lot of chaos throughout the company. Operational burden is also very high, and in some of the groups the Tier 1 support staff are the SDE's 24 hours a day (don't think you'll spend a lot of time coding as an SDE, because in some cases you will not!) -- everyone has heard of the dreaded pager stories, yes they are true! Project execution is like shoving a square peg through a round hole – very little planning is ever done and many times the atmosphere is simply survival. And, for all of this sacrifice and hard-work you put in, end of year reviews are very demoralizing and non-rewarding. The majority of the compensation is focused on stock rewards that vest at an escalated rate through 4 years. If you want to see any of that compensation, you need to hang around for at least that long – this is a rather large commitment and sacrifice so be prepared.