Is that a general Kerouac question are you referring specifically to On The Road, since it is mentioned in the list of things I've read this year? This was actually my third time to read the book and I have to say that with age (that is, as I age) it loses something.
Kerouac is a good gateway for people who haven't really thought about using words to convey complex and convoluted emotions, rather than, say, cohesive thought. But there are authors before and since who are better at it than he was. If you strip away the events, you get storytelling that isn't actually that strong. Kerouac holds you with the action and pace rather than plot, narrative, craft, etc.
But, perhaps those criticisms are too easy to make 50 years after the fact. Classic literature rarely holds its initial impact for a long period of time because it gets copied to the point that the original seems cliché. This is especially true of any of the Beat authors. People tend to get locked up in the mythology of the author and project their envy/admiration on the work rather than evaluate it honestly.
We, the masses, have a bad habit of assuming that self-destructive behavior automatically means brilliant artistic output. Case in point, Lenny Bruce. Dude was not funny. Not even just a little bit. Don't argue with me on this because you will be wrong. But people hold him up as a genius because he destroyed himself. I have long felt that the only thing keeping Bill Cosby from being the greatest comic storyteller of all time is his failure to develop a heroin addiction. So, we look at Kerouac and think: "He smoked and drank himself to death; he must be a good author."
There are flashes of brilliance, but not on the level that the Great Kerouacian Hype Machine would have you believe.
A really interesting thing about On The Road is that it describes an America that is as foreign to the modern American as it would be to someone who's never even been to the country. Kerouac's pre-interstate, pre-fearing-the-world, pre-consumer-centric America cannot be found. Kerouac's America is so foreign that it is difficult for anyone of my generation (and I suspect anyone younger) to believe that such a place ever existed.
It's interesting also, to see how innocent/ignorant Kerouac was in a lot of things. His foray to Mexico is filled with failures of understanding, for example, the way he mentally ties mambo with Mexico (mambo being an American variant of Cuban music).
For all my modern criticisms, though, Kerouac has had massive impact on me. I still have a tendency to copy his style. I always claim to myself that Hemingway is my greatest influence, but my rambling manner betrays a far greater allegiance to Kerouac (and, it has to be said, Bill Bryson [and my grandfather]). I especially do this in the Welsh language, where there doesn't appear to have been any similar author. Literary rebels in Welsh write in unintelligible dialect, whereas Kerouac played with the words themselves (rather than the way the words are said/spelled) and used them to try to give form to the un-shapeable dimensions of what goes on inside our heads and hearts.
Beyond that, the Kerouac mythology has driven me quite a bit as well. Dr. Handy can probably expound on how she and I, under the influence of On The Road, pushed out into the world as best as could be expected of suburban Midwestern kids under the drinking age. And for each of us that served as the foundation for what we've become, what we're becoming. Although, it's quite possible that films like "Smokey and the Bandit" had just as much sway on my desire to travel.
In terms of Kerouac, though, I tend to think that Dharma Bums is a much better book. It probably had greater influence on me than did On The Road.
So, to sum up: Jack Kerouac is good, but so are Bill Cosby, quaint anglophile travel writers and 70s car films. Obviously, I'm not the best person to be talking to about any of this.