I had this book as a child. The magic of this book is that while the background is pure Space Opera the book is more concerned about telling you about design flaws in the engines or where the best museum examples of the spaceships are, than with telling a poor space opera and that makes the whole thing come beautifully alive.
It is my favorite work of mock nonfiction, although it is probably not the best. It might be because the art is evocative and the text brings this out without degenerating in pointless pulpy space opera. It leaves the Space Opera as an imaginative possibility.