If you enjoy this film—

Do yourself a favor and read the novel as well.
It’s a really great example of when experiencing the source material complements the film, and vice versa.
I saw the film first, and loved it, then read the novel a few years later and loved that as well.
The novel is a truly wonderful, poignant and heartfelt warning against overindulgence in mind-altering drugs, written by a man who witnessed the madness firsthand, and lost friends in said madness.
The film is a great visual representation and dramatization of the themes provided by the novel, but there are certain passages in the novel that simply cannot translate to the screen, and it’s worth a read just for those insanely insightful portions of the prose.
Just my humble two cents.