Jehovah's Witnesses is one of the most famous sects in the world, yet it doesn't get anywhere near as much exposure as Scientology. This is probably one of the best faith based movies I've ever seen, mostly because it deals with the emotional and moral consequences the things you are taught to believe can have on those you love in a very realistic way.
The acting is natural and none of the performers feel like people acting for a movie. It was like getting into the look of a real family and their hardships.
As for how Jehovah's Witnesses members themselves are portrayed, the point is not to show them as evil. It's more of a cautionary stance, on whether it's worth jeopardizing your children's lives because of your conviction to follow one certain ideology. The controversy about Jehovah's Witnesses is that you are not allowed to give or receive blood, even in life-threatening circumstances. The mother in this movie is not an inherently bad person, she just can't find a way to balance her love for God and the love for her children. And that has consequences she might wish she would never had to deal with.
This movie will stay with you after you've watched it. I urge those who not only are interested in the subject matter of organized sects to see it, but those who think a lot about beliefs and how they can affect other people in general.