To me this is one of the best popular books on any aspect of diabetes that I have read. The "case histories" of individual's achievements are nothing short of inspirational! If you are type 1, then the information on how to modify the insulin control would be vital and very difficult to assemble from other resources in my view.
Actually, I am not insulin dependent (it's presently unclear whether I am type 2 or LADA) although I probably will be very soon without the large volume of cardio exercise that I am doing. The book doesn't really go into this aspect --- i.e. using glycogen depletion to control blood sugar --- that was the only weakness from my point of view.