I started at Amazon in 2005 and I can definitely say it's an intense place-- I spent most of my 20s at Amazon. Amazon makes you battle-hardened, jaded engineer the longer you are there. There's just no avoiding it. That being said I worked there as long as I did because there were aspects that I did like. For example I think the opportunities there in terms of work / scale are a lot bigger than many other big companies. They are more willing to take risks on people. For example I had no college degree when they hired me. Also there are quite a lot of very smart people working there. So it's not all bad. But intense? Yes.