It was a fairly poorly presented, heavily one-sided piece of "documentary" work. A lot of their claims we're really backed up with anything.
I've no doubt that Wal-Mart is an evil mega-corporation, and we didn't really shop there much before, and we'll certainly never shop there again, but I would have preferred to have a seen a more balanced, better presented piece than what this had to offer.
There were a lot of "Mom and Pop" businesses going "wah wah, Wal-Mart stole my lunch", and frankly, that's capitalism for you, sorry. I can appreciate that the "Mom and Pop" businesses may have provided better conditions for their employees, but that didn't seem to be the focus of those stories, just that various governments provided subsidies for Wal-Mart to come in, and all of the local small businesses had to shut up shop as a result. At no point was there any discussion about sales-tax benefits to the cities that provided incentives for Wal-Mart to move in.
So yeah, the movie was an eye opener, even when taken with a large salt-shaker, but it could have been done a lot better. The user comments on IMDb are quite interesting in and of themselves.