I give 5 stars because the book is well written, interesting, and I think it's quite a breakthrough regarding health.
I started practicing earthing with an earthing mat too while reading this book, and I can definitely feel a tingling in my feet after a work day, or after sport. My recovery after grueling days is significantly better, I can do more and still recover faster (instead of 3 days of muscle soreness, I have only 2). I usually often catch cold when people are ill around me, and since starting earthing, I seem to be much more resilient (might be a coincidence I do not know). I offered one to my mother, and placebo or not, she was able to stop her antiinflammatory drugs, but it was not enough to cease completely her antihypertensive ones (she reduced the dose). She liked the information given in this book, the testimonials, as well as the scientific facts.
I think that health is based upon exercising, good diet, taking supplements, stress management, and earthing may be the missing foundation to all of that.