This Dickens entry suffers in comparison to his other novels I have read by its origins--not because of its first appearance as a serial, for all of Dickens' novels were first published serially, but because it was not at first intended to be a continuing narrative.
Curiosity Shop was begun as disconnected narratives in the weekly journal "Master Humphrey's Clock" which Dickens began in 1840. Master Humphrey, who narrates the first few chapters of Curiosity Shop, was to write a short essay each week for the journal, without a continuing narrative in plan. However, sales diminished when the audience realized that the numbers of the journal would not tell a continuous tale, as they had come to expect with great eagerness from Dickens--so he began with issue #4 of the journal to connect the tale of Little Nell and her wayward grandfather.
Nell was universally loved at the time of original publication, and Dickens' handling of the story led to the kind of popular excitement that today surrounds the newest movie or music release. Think "Dark Knight" levels of popular excitement. But I'm not sure her character, with its maudlin and romantically angelic perfection as drawn by Dickens, ages well. The grandfather, beset by a gambling addiction, is an often unsympathetic character whose addiction-driven actions brought suffering to Nell that no real character would or could endure so patiently.
Nell is mirrored by Kit, her contemporary in age and her grandfather's assistant around the shop. Kit also is perfect to a fault, a reaction Dickens acknowledges by having a character later say of Kit that he found him more likable when he thought Kit guilty of a crime of which Kit was falsely accused and later acquitted!
The villains of the piece, dwarfish and vile Quilp and his hired legal help, siblings Samson and Sarah Brass, are drawn to evil perfection and seem the most completely-realized characters in the book, while humorous relief Dick Swiveller, clerk to the Brasses and friend to all, ends up being the most likable character in the account.
As typical of most Dickens' novels, there is some mystery involved, with all the lose ends resolved by the close, mostly in a happy fashion, although Dickens' handling of Nell's story was the cause of a great outpouring of surprise, anger, and grief by his reading audience when it was published serially. Readers then certainly reacted more viscerally to her angelic being than I did today.
Still, while this is below the other Dickens novels I have read and rated, it is still a very good tale, not to be missed in the Dickens body of work. I just think it suffers in comparison from the disconnectedness of its initial origins from which it never fully recovers in my estimation.