When I have finished a novel and given myself enough time to form my own perspective, my usual practice is to read the relevant Wikipedia article. Generally speaking, I find the commentary on the public reception to the book to be most interesting. With respect to "The Picture of Dorian Gray", while I realised that the novel was controversial, I didn't realise just how hated it was among literary critics and lay people alike. Responses ranged from the suggestion that Wilde was a talented writer who had squandered his immense talent to those who suggested that "The Picture of Dorian Gray" was simply a second-rate version of Robert Louis Stevenson's "The Strange Case of Dr Jekyll and Mr Hyde". Yet over a century later, it is regarded as one of the great works of Western literature.
It struck me that great literature has several things in common. Great literature either wrestles with issues pertinent to the society in which it is written, or existential issues that seem to have eternal significance. Salinger's "The Catcher in the Rye" explored themes such as the loss of innocence, identity and hypocrisy. Huxley's rather prophetic "Brave New World" looked at the issues of conformity and the hegemonic influence of science upon the then contemporary society. Among other things, Hugo's "Les Miserables" tackled the themes of human progress, the criminal justice system and redemption. Each of these novels do not allow the reader to be a passive bystander; rather they are compelled to think about these issues for themselves and come to their own conclusions.
Secondly, it appears to me that nearly all books that become immortal attract controversy. This is probably because many of these books make criticisms that cut rather close to the bone. Dostoevesky's "The Idiot", Wilde's "The Picture of Dorian Gray" and Fitzgerald's "The Great Gatsby" all make rather harsh criticisms of high society, accusing them of hypocrisy and suggesting that they desire style over substance. In this sense, these novels are also subversive because they issue a threat to the established social order. Indeed, it is well known that troops from the North in the American Civil War would quite often carry "Les Miserables" around on their battles.
Thirdly, I would suggest that great novels are well ahead of their time. In exposing the plight of women and their near helplessness in the societal structures of Edwardian England, Virginia Woolf's "Mrs Dalloway" was a forerunner for modern feminism, still decades away. Orwell's "Nineteen Eighty-Four" spoke of the dangers of an increasingly centralised government and the impact that this can have on the freedom of the individual in society. This is an issue which has only really come to real prominence in the last five years with anti-terrorism laws in Australia and the Patriot Act in America. Almost without knowing it at the time, these authors write books which take on prophetic significance.
It is this last point that is of most comfort to me. Books (and commentary) that are popular are not always right, and books that are right are not always popular. Truly profound insights will always take some time to catch on as society struggles to catch up. The writings of Kierkegaard, for instance, never really became popular until after his death. It is the opinions of the future that will stand the test of time while the comforting voice of popularism will wither like the grass in the fields.