I certainly don't bedrudge her success, as a librarian anything that gets kids reading is to be applauded. Professionally, however, I have to make judgements on the grounds of literary merit as well as popularity, and in literary terms Rowling is not a particularly good writer, compared, for instance, with C.S.Lewis, Tolkien, or Philip Pullman. Popularity is not the same as quality, although both can be admired. Dickens was a better novelist than Tom Clancy, or Terry Pratchett, although I admire and read all of them.
To say other writers knock Rowling into a cocked hat doesn't deride Rowling, it merely indicates how inexplicable popular opinion can be. I've read all the HP books, I loved them, I can't wait for the next one, I can't wait for the film, nevertheless Rowling is not as good a writer as Philip Pullman, although he will never be as popular, or encourage as many children to pick up a book and read.