Pros
The best reasons to work for Amazon are that it's the best experience builder and resume builder you will ever have. A year at Amazon is like a dog-year - it's worth 5 of anywhere else. I've had no trouble getting my foot in the door elsewhere simply because I worked for Amazon. Right now also the pay is pretty good because of the stock options, though that didn't use to be the case and certainly there is a belief that Amazon does not share the wealth the way it should.
Kontras
Work life balance is not possible at Amazon. Everything is on "Internet speed" which means all the type-a people who work there run around like they are on some kind of amphetamine. Usually this is unnecessary and causes of lot of unnecessary churn and drama. I was at an all-hands meeting where Jeff Bezos said to the entire workforce that if you want to spend time with your kids then working at Amazon probably isn't for you.