"Fahrenheit 451" is an excellent title for this book. Bradbury is being very sly in using this title. If you consider when the book was published and how far in the future these concepts would have been at this time it is not only sly but also very clever. If you remember your high school science classes you will know that 451 degrees Fahrenheit is the temperature that paper burns. Since the theme of the "firemen" is to burn books instead of put out fires, then you can see how appropriate this title is for the novel and it's theme.
I think it is a great title especially since that is the temp at which paper burns.