Anti-WalMart Campaign?

[Vagos]

I've been reading some things about all this Anti-Wal-Mart business lately, and how some Democrats are raising it as a big political issue. Can someone please give me a crash course on either...
A) Why Wal-Mart is so bad and there's a need for Anti-Wal-Mart campaigns and protests?
or
B) Why it's all just hogwash from the left and why Wal-Mart is not so bad

I'm interested to see hear both sides. I know a little about Wal-Mart, but I'm certainly not an expert on the whole saga, so I'm interested to hear all angles of this thing.