The basis of homeopathy is the use of dilutions. The dilutions are for the most part those of substances which, if undiluted would cause the symptoms being treated, but yet in dilution cause the body to heal itself of those very same symptoms.
I am not a practitioner, but from my own experience that I know that Homoeopathic treatment does work, but it should be carried out by a Homoeopathic practitioner, meaning someone trained and qualified in "Classical Homoeopathy".
Homoeopathy works on animals, and very young children, and therefore cannot be described truefully as placebo. My children were treated from babies successfully, for all sorts of illnesses using homoeopathy. I have also treated foxes successfully for mange using homoeopathic remedies.
The problem with scientific investigations into Homoeopathy is that although science is good at testing conventional medicine, in my personal view it currently has no valid testing techniques for testing homoeopathy properly.
Nevertheless I have linked (under "Sources" below) a webpage which has results for research showing homeopathy works better than placebo (and just for the sake of good order, I would like to point out that I have no connections with the website).
Homoeopathy is indeed holistic. This is because practitioners match each homoeopathic remedy to the patient's entire symptom picture. This means not just all the symptoms of one illness, but the symptoms for all illnesses from which the patient is currently suffering.
Doctors normally describe homeopathy as invalid, but they are not trained in it, and you should make up your own mind.
I hope this helps.