An excellent resource for those w/ arthritis and yoga teachers wanting to help their students with arthritis. Someone new to yoga, though, cannot start with this book. I'd recommend getting some guidance from an experiences yoga teacher before soon any of the asana alone at home.
The information on ankylosing spondylitis, though, is completely out of date and posits ideas about AS that no longer apply, and may have been breaking down in 2008 when the book was published. AS is not "[l]argely a disease of young men" in which "thoracic spine-rib joints and the vertebra-vertebra joints generally fuse in the late teens to early twenties." Fusing is not a tool of diagnosis and is not guaranteed at any age. AS is painful, progressive, under-diagnosed and undertreated, especially because too many doctors still think it's a "man's disease." It's not.