This is an enormous A-Z encyclopedia of 20th (and 21st) century design primarily in Europe and North America. Other than a couple extended photo essays about American and Italian design in the post WWII years, the book really is an alphabetical listing of all the major designers, products, and movements in the design world. There are hundreds of photos - several on each page.
I was struck by the continuity of design in the past 100 years, especially in architecture, furniture, and interior design. Most of what we take to be 'modern' today springs directly from the ideas of the 1920s; and what must have seemed at that time as radical differences between design movements (Bauhaus, art-deco, etc.) have now been merged into a cohesive, mass-produced whole.
With rare exceptions, design seems to have reached a kind of peak in the late 50s. The book had a definite 'center of gravity' around 1960 - most of the really extraordinary examples of design had been done by then, and most of what came after was either a direct copy of the design of that period, or was of clearly inferior quality. There are exceptions, of course. The iMac and iPod designs stand out. But the period from 1946 to 1960 was a time of amazing design across all genres from vehicles to architecture to dinnerware.
The book works well as an overview, and is an excellent photo-sampler of the past century of design. It might have been improved with a little more analysis (or at least opinion) about why certain designs worked and others didn't. And a little deeper discussion of the design process and how important designers dealt with constraints would have been interesting. But it is already a very large book - too large and too to hold comfortably for any period of time.