I did work there for a few months, my son has been working there for 9 months and my DH works there too, so I am a bit biased.
When I worked there, pre-DH working there, they were very strict about the hours I worked. I was not allowed to clock in sooner than 5 minutes before a shift or 5 minutes after. We had to take breaks at the scheduled time. If we were off the clock and a manager or co-worker needed something, we had to reclock in and talk to them or whatever. I was hired to work 30 hours a week and was only scheduled for 30 hours a week and only worked during the hours I said I was available.
My son has had similar experiences and has never had to work a day/time he isn't scheduled for nor more hours than he was hired for.
From what I understand( from another anti-walmart post), WM had trouble with forced OT and there were lawsuits? I think this was years ago and they have sinced change policy according to that.
As far as treating workers nicely I never had any issues and my manager was extremely nice. DS's managers are very nice too.