What made it so difficult? Well, it's expensive to go to multiple period locations with a huge cast. And what have these historical literary figures to tell us now? Kerouac and poet Allen Ginsberg had an enormous impact on the culture, spawning the Beat Generation which led in turn to the 60s counterculture. They, like many in my parents' generation, were rebelling against the conservative mores of the time, and jazz, booze, sex, misogyny, creativity and irresponsibility were all part of the picture.
Rivera and Salles ran a four-week boot camp for the actors in Montreal, where they steeped themselves in books and films and met and interviewed many survivors and children of the Beat circle. Salles stresses that he's showing the formative years before the Beats came to life. The script is thoughtful and rigorously structured against the real criss-crossing itinerary, which the filmmakers re-traced.
And yet as fascinating and authentic as the movie is, it all comes down to Dean Moriarty. There's a reason why Kerouac (embodied in "On the Road" as writer Sal, played by Sam Riley, star of "Control") and Tom Wolfe ("The Electric Kool-Aid Acid Test") devoted so many pages writing about Neal Cassady (aka Moriarty). He was a charismatic, larger-than-life speed-freak babblemouth who mesmerized the men and women around him, from multiple wives (the first two are well-played by Kristen Stewart and Kirsten Dunst, respectively) to poet Allen Ginsberg (Tom Sturridge plays "Carlo"), with whom Moriarty/Cassady had a sexual relationship (as depicted in the less successful "Howl").