Pros
Ships a lot in a really short time. Leading the way in digital media. Amazon talks a lot about it "still being day one" in that there is a lot of opportunity in the space they are in. That definitely is true. I got lucky with my team for work-life balance. Compared to a lot of others, I have a pretty sane work life.
Cons
Avoid working in the Kindle organization unless you like really political environments. There are some people who are hired with the sole purpose to nag other teams to deliver on their schedule. If you think android fragmentation is bad, try dealing with Kindle internal teams. Components will make changes that break consumers and provide no backwards compatibility story besides telling people to fork their own codebase. People in the Kindle org are very quick to pass blame to others and do things to just cover their own butt. Based on the company values, I'm very surprised that the Kindle organization behaves the way they do. They've hired too many ex-Microsoft who brought the poor culture along (see the article about Microsoft lost decade). Promotions seem nearly impossible here too. Promotion committees are very quick to dismiss a promotion on a single peer feedback even though there is overwhelming good feedback. Also, if you do not have a lot of other people on your team at a higher level than you, you cannot get the required endorsement of someone at that level to get promoted.