Pros
The entreprenuerial culture makes Amazon a great place to grow your career if you're the kind of person who will not only pick up the ball and run with it, but will make the ball in the first place. If you're looking for someone to lead you by the hand, though, Amazon's not for you.
Cons
The company can be frugal to the point of being penny-wise and pound-foolish, and communication between orgs isn't great. Maintaining work-life balance is also difficult, though in my experience not as tough as it's sometimes cracked up to be--you just need to set and maintain the boundaries that work for you. I'm in a fairly supportive group, though--I've heard horror stories from colleagues in other areas of the company, and there's a ton of turnover in some areas.