I was so looking forward to this movie when it was in post production and the schedule was announced. Boy, was I disappointed. I am not saying not to watch it. It is well worth the time. But do not expect to learn how to survive. The producers and directors made it abundantly clear that "The survivors of a nuclear war would envy the dead." It was an anti-nuclear weapons propaganda movie from the get go.
Pretty much every person that had a reasonable chance to survive, and even help other people, simply threw those chances away out of what I call the attitude of nuclear war induced despair. That, hey, it is nuclear war. We do not deserve to live since we let a nuclear war happen. They did things so obviously not wise that it was painful to watch at times.
But as an historical footnote of the anti nuclear/anti war fervor of the time, and a really impressive set of negative lessons, with virtually no redeeming positive ones, it is a good watch. The special effects at the time were well done, and the movie was quite well made, with a good budget. But that is to be expected with the people involved in the anti nuke movement at the time.
Do watch it. But, as preppers, be prepared to be more than a bit annoyed at times as you do.
Just my reserved opinion.