I checked out Kevin Walsh's Forgotten New York: Views of a Lost Metropolis from being a fan of his
Forgotten NY site, yet that actually detracts from the book a bit. The website is jam-packed with details and information, while the book has to leave things out. I felt that parts of Queens in particular were really shortchanged in the book, especially the Metropolitan Avenue strip and Ridgewood, while Manhattan could really be a book of its own, much larger than what's represented here. The book also, by its very nature, is a frozen snapshot of the time when it was published, while five years is an eternity in New York real estate.
It's good and filled with information, but it really makes me want to browse the website!