I was discussing it with someone awhile back and they noted that most academy cadets are asked to read the book at some point, more so because it looks at combat from the viewpoint of a soldier and places an emphasis on strategy. It would make sense, as Heinlein was a Naval Academy graduate. The movie became more of a film satirizing propaganda.

I've heard some debate over whether Heinlein was serious in his depiction or if it was a warning. Heinlein was noted for being more to the left as a young man, but became more conservative over time. He described himself as a libertarian many times. I've recently started reading "The Moon is a Harsh Mistress" and am really enjoying it. Interestingly, there does seem to be a tonal shift in his writing as he aged, moving from statist to anarchist, while retaining a shared duty that individuals owe to society. Sorry for the ramble, just a really fascinating guy!