I read the book as a teen, and enjoyed the movie immensely as an adult. At both pre-WWW times I had no idea that Heinlein wrote the book as a protest against stopping nuclear testing. I always thought the book was satire. Maybe the irony is that Heinlein didn't realize he was sending up his own opinion in his own book.

In any case, I loved the movie even more than the book, and for the same reasons.