I have never watched the BBC version of Cranford, but I had a general sense that it was about a small village which is dominated by the women who live there. Since I love, love, love Mrs. Gaskell's book North and South, this seemed a good companion for it.
First of all, the tone is completely different from N&S. Where North and South is filled with the drama of two strong-minded characters separated by class, Cranford is an episodic tale of a backwater village that is classbound and extremely conscious of manners. Told from the point of view of Mary Smith, a young woman who visits Cranford, we are shown the lives of a small group of spinsters and widows who are scraping by financially. They visit, they play cards, they gossip. Miss Matty is the heart of this group. She is sweetly naive, and open-hearted to her neighbors. Her older sister Deborah dominates her with strong opinions. What gives the book a gently comic sense of the absurd are Mary's observations of the women of the village.
Cranford falls between Dickens' social comic novels and Anthony Trollope's Barsetshire novels. It is a close observation of the lives of mid-19th century women, from their financial situations to their concern about fashion and status.