The letters are the only extended autobiographical writing by Dickens that has survived. Attempts at writing a diary seldom lasted long and for the most part the manuscripts are lost, while a memoir of his childhood was discontinued and converted into some of the early chapters of David Copperfield. The letters therefore give the most immediate and vivid expression of Dickens's life as seen by himself, even though they rarely examine his interior life. They give a unique insight into the way Dickens's processes of composition worked as he wrestled with the novels he published and considered others which were never written, such as the "book where of the whole story shall be on the top of the Great St. Bernard". Dickens's almost constant travelling is also reflected.

Though some letters are in private hands, most are now in libraries and public institutions.The largest collection is held by the Charles Dickens Museum in London, the second largest by the Victoria and Albert Museum, and the third largest by the Morgan Library & Museum in New York; other extensive collections are held by the British Library, the New York Public Library, the Huntington Library, and the Free Library of Philadelphia.