I think, this book is a masterpiece, it hits every spot. In terms of language, plot, rhyme, general idea it is absolutely flawless.
In addition to spotless literary style, it can be seen as a kind of a historical textbook, covering life in London through the ages, giving a broad picture of feelings and aspirations, habits and customs. Some vignettes portray historical figures, some - ordinary people, and though it seems that the vignettes are short standalones, they are somehow connected, one is woven into another, like in a sonnet sequence. It's hauntingly beautiful.
For me it's A Perfect Book and unforgettable reading experience