I remember reading about Amazon making warehouse employees sign a non-compete agreement - a stipulation that was rather quickly reversed after The Verge and other publications exposed it. What other examples of terribleness have you read about?
There are articles on how horrible the warehouse conditions are. (For example, http://www.motherjones.com/politics/2012/02/mac-mcclelland-f...). Note that I'm not trying to condone that perception, just merely observing that it exists in tandem with Walmart's (whose problems are well-known).
This came up on reddit a while ago; the general tone of the conversation I got was that it really depends on which warehouse you're working at, some had horrible managers and others had really good working experiences. It's still strange that its like that though.