Is holistic medicine actually? Legitimate?

Yes, it is. Holistic medicine is a legitimate field. Its body of expertise includes whole-person health, nutrition, mind-body interventions, tcm/acupuncture, herbs, energy medicine, homeopathy, manual medicine, spirituality, and more. Physicians who practice holistic medicine come from from many specialties. There is an american board of holistic integrative medicine: see http://www.Abihm.Org/ for info.
Proven vs unproven. By definition, "alternative" is different than modern western medicine. Generally any drug, herb, treatment, or procedure that stands up to rigorous scientific scrutiny is included in modern medicine. The problem is that many alternative practices, herbs etc do not stand up to scientific scrutiny and cannot be shown to work. They therefore remain "alternative". Be careful and watch your wallet.
They are trying. The herbalists, homeopaths, energy-medicine people, spiritual-healing folks and their kind are organizing themselves to exercise some control over their fields, throw the obvious quacks out, and figure out what is evidence-based and what is just placebos and feel-good sweet-talk -- and even that has its place. You may disagree; i honor them for this and am watching with interest.