The time of transition

Dickens, 'the last of the great men', experienced a marked transition between his early books and his later work. Chesterton discusses this transition from the 'last of a quite definite series, the early novels of Dickens', 'Dombey and Son', to 'David Copperfield' and 'Bleak House'. As Chesterton summarizes: 'Very coarsely, the case may be put by saying that he diminished, in the story as a whole, the practice of pure caricature. Still more coarsely it may be put in the phrase that he began to practice realism.'
Chesterton is not undividedly positive about this transition; though he admits that the later novels are in some aspects better than the first novels, he is no fan of realism per se. Nowhere is this more stressed than in his discussion of Dickens' most autobiographical work: 'David Copperfield'. He perceived

'that if an autobiography is really to be honest it must be turned into a work of fiction. If it is really to tell the truth, it must at all costs profess not to. [-] A touch of fiction is almost always essential to the real conveying of fact, because fact, as experienced, has a fragmentariness which is bewildering at first hand and quite blinding at second hand. Facts have at least to be sorted into compartments and the proper head and tail given to each. [-] Without this selection and completion our life seems a tangle of unfinished tales'. 

I would say that this same principle goes for all Dickens' realistic novels: in a sense, the character and the plot are 'exaggerated'; this is only done, however, so that we can better recognize these more universal characters and happenings.