In Dickens and His Readers: Aspects of Novel Criticism Since 1836, George H. Ford quoted George Borrow, who wrote in 1838 that "Everybody was in raptures over a certain Oliver Twist that had just come out." Readers of the time, far from being dismayed by the dark quality of the book, loved it. An exception was Thackeray, who mocked Dickens's portrayal of Nancy, saying she was sentimentally and unrealistically presented. Dickens was so upset by this comment that he wrote an angry reply to Thackeray in the preface to the book, according to Ford. Ford also noted that although most readers loved the book, some were indeed alienated: "the kind of reader who cannot bear to be ruffled by violent emotions."

Some of these readers were critics who were dismayed by its presentation of criminals, work-house inmates, and illegitimacy. According to Ford, Henry Fox wrote that the book was "painful and revolting"; Fox quoted Lady Carlyle, who commented, "I know that there are such unfortunate beings as pick-pockets and street walkers . . . but I own I do not wish to hear what they say to one another." Fox also wrote that although the book seemed to be such a fad that few dared to speak against it, "I suspect, when the novelty and the fashion of admiring [it and other books] wear off, they will sink to their proper level."

For these readers, Dickens's attacks on the social institutions responsible for crime and poverty were not considered enough to make up for the fact that he was presenting indecent, wretched characters to his supposedly sheltered readers. However, in Critical Studies of the Works of Charles Dickens, George Gissing noted that these views were not shared by most readers and wrote, "When criticism had said its say, the world did homage to a genial moralist, a keen satirist, and a leader in literature."

Gissing did remark on what he saw as the book's flaws: "Attempting a continued story, the author shows at once his weakest side, the defect which he will never outgrow. There is no coherency in the structure of the thing; the plotting is utterly without ingenuity; the mysteries are so artificial as to be altogether uninteresting." However, he did note that at the time Dickens wrote the book, fiction was in its infancy, and readers were not nearly as demanding as they are now. Tight, complex, and realistic plotting had yet to be developed, so modern readers cannot fault Dickens for not using it. If modern readers overlook the creaky plot mechanisms, what remains is "a very impressive picture of the wretched and the horrible," with realistic descriptions of the London streets and people, their daily habits, voices, food, and clothing.

Joseph Gold, in Charles Dickens: Radical Moralist, wrote that it was not surprising that critics in Dickens's day were upset by the book, because what Dickens did was to "humanize the criminal. This was not readily forgiven, for to humanize the criminal is to show his relationship to the reader, who would prefer to regard him as another species." This was very different from previous novels, which either romanticized criminals as gallant outcasts or as complete monsters, utterly inhuman.

In Modern Critical Views: Dickens, J. Hillis Miller commented that the book was flawed mainly because of its depiction of Oliver, who from beginning to end is a tool of others. He does rebel against the thieves who try to mold him into one of them, but in the end he succumbs to the molding of Mr. Brownlow and friends; Mr. Brownlow adopts him, and he becomes what Brownlow wants him to be. He has not solved the dilemmas of his parentage and of determining on his own what he wants to be and to do. He lives happily ever after, but "only by living in a perpetual childhood of submission to protection and direction from without."

Geoffrey Thurley, in The Dickens Myth, remarked that of course the book's plot is absurd but that the book's enduring value stems from its "moral vision" and its depiction of the confrontation between good and evil.

In Dickens: A Collection of Critical Essays, John Bayley wrote that the book, unlike its predecessor, The Pickwick Papers, was "a modern novel," as shown by the fact that despite its flaws it can still touch the modern reader.