Stephen King has written some great books (I’d even lump Dark Tower into Great Books, uppercase) and some complete, utter, writing-just-for-money crap. I think he’s even said as much.
Some people like to think writing is all about being Pure and True to the Muse, so his Sellout Years offend them.
Some people just don’t like genre fiction, so he’s a Genre Author, cursed with the mark of Cain (-2 to Literary Greatness, +2 to Bestseller).
Some people just read a bad book of his and have decided they don’t like him.
Some people have read a LOT of his books and figure the crap outweighs the good stuff.
Some people don’t like that he tends to repeat himself and doesn’t seem to strive for originality.
Some people don’t like his rather workmanlike writing style. King isn’t going to wow you with his elaborate metaphors. I’d put him with R.A. Salvatore: Just decent enough to move the story along, most of the time.
Some people think reading a book–any book–should be a Deep Life-Changing Deeply Moving Experience and find no joy in your basic potboilers, decent beach reads, and books that have no literary value whatsoever but are fun to read anyway. One wonders what these people do for cookbooks. (“Add a cup of flour…which never liked its mother anyway and sat on the floor crying while she yelled at his daddy, Pinch of Salt.”).
On a personal level, I haven’t read too much of his writing: Salem’s Lost, Eyes of the Dragon, The Stand, Thinner, The Talisman, Black House and the Dark Tower books are all the fiction of his I can remember reading. I enjoyed all of them and think Dark Tower is magnificent. I respect him a lot for even trying something like bringing all these characters from his other works into his “magnificent octopus,” and admit there’s a canniness in bringing characters from other books into this one, since I just had to find out all about Salem’s Lot, once I spent some time with Father Callahan. I also found On Writing to be a great, great book and he had a whole lot to say for a crappy pulp writer. To sum up: I’ve enjoyed most of his books, respects that he admits to being a hack, and think he’s a whole lot smarter than people give him credit for.
I also think when the English majors of the future are going to be trying to figure out our culture, King’s who they’re going to turn to, not a writer with only 200 copies of one book in print that all the critics love.