Howdy Ann,
I have several
books on herbalism, have taken classes in herbalism and have used herbalism for my own well-being; I would recommend a few books and a thoughtful way to evaluate what other books you might purchase. First, it would be best to buy an herbal for your area, meaning a book on the plants that grow where you are. Second, It also would behoove anyone interested in herbalism to balance the lore and tradition of the various cultures who used herbalism with the knowledge of modern herbalism gained by peer reviewing, lab research and clinical work that has been done in the past few decades.
The following are some books I have: M. Moore's
Medicinal plants of... he wrote three books for three different areas, the mountain West, Pacific West and Desert and canyon West; Hoffman's Medical herbalism; Kings American Dispensatory which represents the height of the Eclectic tradition at the beginning of the 20th Century. There are also superb herbals written by Rosemary Gladstar and Susan Weed and others who merit a look before you decide. You might pop by the American Herbalist Guild ( AHG) and nose around.
As for the book you mentioned, it is confusing to me when I looked it up. Flashy advertisements and language and yet several authors of several different books; It seems as if different people are publishing a book whose copyright has expired and is now in the public domain. Perhaps it's a great book, however prima facie, it doesn't look as promising as what it promises. I hope someone else can offer more constructive feedback on it. And as always if you're intuition says this is the one well, go for it.
Best of luck on finding what you are looking for!
Thomas