Pros
At Amazon, a developer is like a clown in circus -- must be able to perform all kinds of tricks on acceptable level to get the job done. Same time, you will learn a great deal and will understands IT end-to-end. For an SDE, being a part of Amazon Web Services gives you the edge to work on truly high-scale projects and buys you a free ticket to many other work places when you decide to leave. Interestingly enough, right now there is an exodus of Microsoft people willing to switch over and work for AWS. Amazon is definitely not for everyone and requires a lot of effort to stay sane. Yes, you will be stressed out almost every day: either being on-call fixing stuff you never seen before (the timer is ticking btw) or managing unrealistic project deadlines or very often both in parallel. However you may look at it from another angle -- this is how people bond and develop trust when they go through hell together. Your Amazon co-workers will be like your good old army friends forever. On-call can be horrible depending on the team or time of the year but don't create illusions because the industry is shifting the majority of software jobs towards developing and running services. Amazon will take you ahead on that and you will learn how it's done on the large scale. As a matter of fact, at Microsoft more and more devs carrying a pager too and also staying sleepless (yeah a bit to the East, in Redmond.) I like the fact that people don't slack around here and majority of managers are occupied with a plenty of real issues and getting paged too. There is very little of bureaucracy here: know the right thing to do? then go and just do it! You will feel empowered when you realize that you control such a huge fleet. You will find a lot of smart people around you and most of the time they say what they mean. After tasting Amazon it is hard to go back to the traditional IT company where everything is slow and managers are afraid of changes. If you prefer true ownership of what you are given, you will find Amazon a decent company to work for.
Kontras
The attrition is very high which is not good for the moral but again those people who are leaving now will call you some day with a job offer. Agree with other reviews that you should know a lot of stuff before joining Amazon because there is no time to learn or take a class on anything. It is a sink-or-swim environment. Taking this into account, I would say that entering Amazon is probably better as the second job when you already know quite a few things, learned to code well, understand how to manage priorities, and now it's time to turn your brain on full throttle. Amazon has the worst choice of medical plans across pretty much all high-tech non-startup companies in the area and I don't count MS at all here. Honestly, I do not recommend Amazon to my friends because it is not a comfortable place to work at. There is a lot of pain going on here and I'm not enjoying it but for myself I consider it as the growing pain.