Published back in 1971, this novel is a set in a hypothetical post-Soviet-invasion United States. There is no widespread resistance nor rebellion - the people simply accept one overlord government system in lieu of another, and get on with their lives. A few, however, are sent to what amount to re-education camps, and that is where the story takes off, but in unexpected directions. Much of the novel explores the reality of living alone both on a 'ranch' (main character before the Soviet invasion) and in the wilderness (after escaping from the camp). This element of the novel (living a solitary life) is essentially auto-biographical.
I found the novel interesting, but not as compelling as the "action thrillers" of today (and an interesting comparison in that regard). Ultimately, I see the author's view of life as excessively pessimistic, but I certainly can't say he was wrong to feel that way.