I watched this movie this week (thank you Tubi) for the first time in at least fifty years. I remembered it so clearly from seeing it all those years ago as a child. I was surprised how accurate my memory of it is. It certainly made an impression on me back then and I am pleased that I still find it such a good film.
I have looked up reviews of it and while it is overall well thought of I feel that it has been underrated. I imagine a lot of that has to do with it being thought of as a sci-fi/horror flick and nothing more. (I do not mean to denigrate sci-fi/horror - I am a lover of the genre, particularly those from the 1950s).
I think there is a lot more going on than just the framework post-apocalyptic story. To me it's more about the characters and people in general, in the same way Lord of the Flies is about more than a bunch of schoolboys having an adventure.
It should be noted that when this was made the story of a post-atomic world was a new thing, not yet a bit of a cliche.
I'm very fond of black and white photography and this is very well done here, There's a grandeur captured in many scenes, a feeling that what is happening to these people is important. (It reminds me somewhat of the cinematography in films of Leni Riefenstahl (she's a controversial figure but she knew how to use film.)). I particularly like that so much is conveyed visually without dialogue or commentary (often in just one or two simple shots) - which is something that should happen in a visual media.
Many reviews commented on the fact that these were unknown actors, as though that made their performances somehow lesser. All of them were excellent - I have no quibbles at all with any of them.