"Peaceable Kingdom" is at times sad, shocking, and depressing... but it is ultimately uplifting and inspiring. Who knew all these terrible things were happening to farm animals? We must be their voice, and work to change how they are treated. The most effective way, of course, is to adopt a vegan diet.
It is important to see farm animals for what they really are -- sentient beings who can feel physical pain and who can suffer psycologically from intense confinement (not to mention fear). I have been to Farm Sanctuary's CA shelter, both as a visitor and as an intern, and it helps to see animals like pigs or cows or turkeys being cared for so lovingly after enduring various cruelties at the hands of humans. You discover that, just like our dogs and cats, each individual has his or her own personality, likes and dislikes (such as certain sleeping places or favorite foods), and generally likes to interact with people. "Peaceable Kingdom" conveys this very well, I think.
I have seen this movie 3 times so far, and it makes me laugh and cry every time. I cannot recommend it enough.