Is Fahrenheit 451 a metaphor?

It's a metaphor for socialism, whether fascist or communist. It exemplifies the control of ideas in a controlled society. The conversation which Beatty has with Montag to show how books contain ideas which confuse people is intended to show the socialist theory that removing ideas limits the range of thoughts people can have and so reduces any anti-social thoughts they might have. No ideas - no thoughts - no reactionaries.