The novel is so very early-70s.

But its path from 70s to dystopia is better plotted. Most others have a massive gap ( and here everyone gives up what they value and plays dead ) where you just have to accept that resistance magically disappears or was never present. It shows that the tyrant must deliver "value" for the abandonment of agency. Post Snowden we understand that.

Further it is the only dystopian novel ( pre-Soviet collapse ) which understands that the vacuum caused by the removal of a tyranny does not create freedom in a population whose living memory does not include the practice of freedom.

But yeah, there may be reasons Ira Levin is not known as a science fiction author. :)

Dante