This is the 'bible' of Genus Hosta. Other experts very rarely disagree with this book. A hostaholic required book. Especially neat is that the author is active on a few internet discussion groups and willingly responds to clarification questions.
George Schmid is THE botanical expert on hostas. This book leans more to the botanical description side of things than the casual gardener's needs. However, for a serious collector, with a deeper interest in the genus, I would consider it essential.
This book contains much more than just nice pictures of hostas and information about growing them. It discusses the history of Hostas, telling about their names, background, cultivation, and much more. It also includes information about propagating, hybridizing, and showing hostas. It is an older book, and the color pictures are presented in "plates" in the center of the book. There are also some black and white photos in the text area.
The book is currently out of print, so if you see one at a reasonable price, and you think you might like to have it...get it!
I particularly enjoyed the detailed information on the species hostas, gaining a better understanding of the meaning of non-English names, and the environments where hostas originated. Mr Schmid also shows the name of the hosta in Japanese language characters for those who can read them. Hosta collectors and hybridizers will often classify the shape or "type" of hosta by the species "Montana-type" or "kikutii-type" and this book helps your understanding of what that means.
Mr. Schmid also provides updates on the species at www.hostalibrary.org.