I know one guy, a developer for AWS (their web services division.)
Great comp, good teammates, average management, interesting stock package, and interesting work but DAMN did he work a lot of hours of unpaid OT. It struck me as the sort of place that provides awesome comp with the expectation that you will really devote yourself to the job. He stayed three years and left for something less demanding. (Failed, actually, new job is just as demanding.)
That being said, from the outside (me) looking in (at him) it struck me as a pretty standard IT/programming job. Most of them are fast-paced with high expectations.
Also, it's important to note that there can be wide variations between different groups and departments, even within companies. In my experience, some simply work harder than others.