A Google user
While the critical reviews of this book are perfectly valid, this book was central to the development of architectural and social theory during the late 19th century. It was especially influential as a precursor to William Morris and the Arts and Crafts movement (including Stickley, F.L. Wright, etc.).
It is a little dry and outdated, but as important to the history of architecture and socialism as Descartes (WAY more dry of a writer by the way!) was to philosophy and religion.