Yebbut now you've read it, you can say all that - what did you get out of the other readathons you mention, hmmm? And it took a lot less time than the Bible or the Silmarillion, amiright?
The Bible is a collection of tattered bits of scribblings and oral tradition made by various people over the course of centuries, curated and edited by people with a keen understanding of human nature and absolutely no interest in reality.
The Silmarillion is a collection of tattered bits of scribblings and world building made by two people over the course of half a century, curated and edited by Christopher Tolkien, the one person on the planet with a keen understanding of his father's work. Some of it is amazing. e.g. The Fall of Gondolin and Beren and Luthien come to mind (both were later extracted into their own self-contained novels), a lot of it is very dry worldbuilding and glum elvish poetry.
Fahrenheit 451 is self-satisfied dribble created by one person over the course of 9 days that makes the mistake of thinking that it is far cleverer and subversive than it actually is.
What if firemen ... get this... set fires! *mind-exploding.gif*
Bradbury was a decent sci-fi author but his attempts at social commentary failed to be remotely as meaningful or evocative as even the weakest of Orwell's works.
Edit: On reflection I think I'm being unfair to Bradbury and the novel. In the prevailing context where other people finding F451 worthy of all the praise in the world, I found it sorely wanting.
In the context of a novel smushed into existence by combining several short sci-fi short stories he'd already written into one, it's not terrible. It's a passable example of genre fiction, although the abuse of metaphor makes it a challenging read - but not interestingly so.