Reading for the first time a great book at an older age is an extraordinary pleasure: it's a different experience (we cannot say it's a greater or lesser experience) than that of reading it in one's youth.
Youth brings to reading—as to any other experience—a special taste and confers a special importance to the process.
With maturity, one appreciates (you should appreciate, at least) more details and different layers of a literary work, sometimes even more meanings.
Are you reading, or re-discovering a book it marked you—differently—in your youth? Is it a classic?