Vignelli Transit Maps by Peter B. Lloyd and Mark Ovenden is the story of Massimo Vignelli’s famous (infamous?) 1972 map of the New York City subway system. The map was controversial because it ignored geographic and station location and stuck to a strict 45- and 90-degree grid, and was eventually replaced by the MTA in 1979. You can see a high-resolution image of the map here.
The book covers the story and people behind the map, as well as the importance of transit maps and how they are designed. There are a number of interesting details on map features such typeface, colour, and cost as well as lovely images of the maps. Where the book does fall a bit short is on answering the question of whether the map was better or worse than those that came before and after it. Even though the book is rather large, some of the maps are illegible because they require even larger formats.
I think Vignelli Transit Maps is a nice companion to the 2007 work Transit Maps of the World. The former will give you some of the tools to help understand that thoughts that went into some of the later. I picked up my copy of Vignelli second-hand for much less than the Amazon price, but I would say it’s worth it if subway maps are an interest of yours.