Very uplifting ++spoilers

I've seen much on the message boards about this being a bleak film. However , the director did a wonderful job portraying the ferocity of life and it's tenacious ability to emerge out of seeming worthlessness. From composting the corpses for his garden, animalistically heightened senses of the characters, or re-discovering old world ingenuity (ie the maggots) we see that humans, as an organism, are strong enough to survive almost any future dystopia. Our moral survival is the real issue, however.
I think that's where the character's portrayals became so powerful despite the lack of dialogue or thrilling action. Milja basically allowed herself to be prostituted by her "mother". When she felt loved by the Survivalist, and worthy for a greater good, she abandoned her past ways and destroyed the evil that was manipulating her. It was a rebirth. She would not use deceit or murder anymore to stay alive. The Survivalist came to grips with his cowardly act of laming his brother. Augustus was sacrificed involuntarily and had no choice in the matter, but the Survivalist was willing and resolved to die if it meant Milja's survival.
We also know that Milja finally found a community that was able to survive on a biological and moral level. The encampment she found had large fields being worked by many individuals. Young and old seemed to work, and the gate guards were male and female. Most telling would have to be the biblical quote on the fence (Peter 4:7) which highly suggests this community follows a moral code for everyone's benefit. Sure, humanity looks like it was set back a few hundred years (despite some modern weapons) but it ultimately flourished and gravitated towards an existence above the animals. One of hope, rebirth, and decency.