Chris Pestacchi It's about the breakdown and rebirth of civilization; technology becomes irrelevant almost immediately in the book.
Nick I just finished re-reading this book for the first time in 25 years or so (the original version, not the bloated uncut version). I have to say that it holds up perfectly well. The impact may be even greater today considering the technical advancement (and our reliance on it) that has taken place since the book was first published.
This answer contains spoilers… (view spoiler)[Minor spoiler : The only thing that felt dated to me was that the military was able to control the media and keep news from spreading for so long. Today with the internet, no way that would happen. Other than that technology really isn’t relevant in the book. I’m currently rereading it and it holds up. Give it a try! (hide spoiler)]