Yeah, I think On The Road is maybe one of those books that was very important, groundbreaking and so on at the time it was published, but is so of-its-time that it's hard for some people (well me, at any rate) to appreciate it out of its context. Lovecraft is another author who is often described as a "good bad writer", although in exactly the opposite way from Kerouac, I suppose.
My beef with The Great Gatsby is that while it was undoubtedly very stylishly written, I just found it kind of pointless...the story line meandered along, almost as if in a daze...perhaps that is ironically the whole point, since it's a book about stylish, pointless people. I should point out that I read it at school for my English Lit GCSE, which is often not a great way to really get the best out of a book - maybe I'd get more out of it now, I don't know.