Ray Bradbury is well-known for his incredibly descriptive style. He employs figurative language (mostly similes, metaphors, and personification) throughout the novel and enriches his story with symbolism. That's one of the reasons this novel is considered a classic: Bradbury's rich use of language. These devices bring the story to life, adding levels of meaning to the surface plot. For example, the first paragraph reveals Montag's love for his job.
It was a special pleasure to see things eaten, to see things blackened and changed. With the brass nozzle in his fists, with this great python spitting its venomous kerosene upon the world, the blood pounded in his head, and his hands were the hands of some amazing conductor playing all the symphonies of blazing and burning to bring down the tatters and charcoal ruins of history.
Notice the figurative language in bold. The comparison of the hose to a venomous snake shows the power Montag feels when starting fires. Comparing him to a conductor shows that he feels he's a creator, bringing something positive to society. These comparisons make Montag's eventual rejection of his job that much more stunning. Because we see the level of enjoyment and contentment at the beginning, his character shift is much more dramatic.
The symbolism throughout the novel is important as well. Even the titles of the sections are symbols. For example, "The Sieve and the Salmander" represent Montag's mind (like a sieve, sorting through this new information), and the image of the fire truck (the salamander). Some symbols transform in meaning over the course of the story. One of these symbols is the most prominent in the novel: fire. Throughout most of the story, it is a destructive force, immolating books and the freedom of thought that books represent. Yet later, when Montag has escaped and finds other refugees, fire becomes a sign of connection, a renewal of human relationships.
Bradbury's gift of language is the reason this book endures. It's not just a warning of the dangers of technology; it's a glimpse at the nature of humanity and human relationships.