Its a scathing critque of the fast-food industry.
I've butchered pretty much every type of animal and have been to plants like the one shown in this movie, but watching this really hit home.
After I watched this, I stopped eating meat that I don't know where it came from or how it is processed. There is a huge, menacing industry behind all the nasty shit we put in our mouths everyday. While it treats both humans and animals like shit, it also drives out independent businesses. It then uses this money to influence politicians to keep its industry legal.
If you have a chance to see this movie, please do. You won't be able to eat fast food in good conscience ever again.
Its a book, too.