I've used it but know that it doesn't last as long as other salon hair colors. I find that it fades within 2 weeks and doesn't cover gray as long but it is healthier for your hair so they say.
there is no bleach in permanent hair color. Color won't lift color so to go lighter it would not have worked on previous colored hair ( shaft & ends)I used it for a few months. The color always seemed too dark to me and when I got in touch with them they had some work arounds, but it was still darker than what I wanted. When I wanted to go a shade lighter they said it wouldn’t work for me because of my gray areas and the fact that they don’t use bleach (which is why it is healthier). I really just wanted to get back to the dark blonde color I used to have before the gray hair and before I used their product.
I do think if you are looking to go a little darker or cover gray with a dark color you will be fine.
I had a difficult time finding the shade I wanted (light golden brown) a few years ago. They seemed to only offer medium brown and darker (level 5) or blonde (level 8). Their work around was to mix two different dyes in one developer bottle to get the shade I wanted. It worked but then I had to order two kits at a time to get both tubes of color.
OP-What are you trying to achieve with hair color? Lighter, darker, just something different, gray coverage, save money?
I have used Overtone too. I am glad you reminded me maybe I will use the conditioner again to see if my color lasts longer. If you have dark hair it is really only a conditioner and does not cover gray.Overtone is another good natural option. I stopped coloring my hair 3 years ago and have been using their various Gray formulas to achieve gray coverage and highlights. It doesn't cover my gray completely but it turns the gray into a glossy highlight. It is also like a deep conditioner and my hair is so much healthier. I was able to do a body perm to give my hair more body which I could never do when I used to color my hair (salon every 10 weeks and at home root touch up every 2-3)