The shampoo works great if you know why you're using it. The title in the description is wrong, the shampoo is meant to remove yellow tones from natural white hair (for dyed hair, there is a purple shampoo available). If you have dyed hair, then the yellowing is fading of your color and you need a blue or purple shampoo to fix the color (blue for brunettes, purple for blondes). If you have naturally gray or white hair, then you want a shampoo like this to clean the yellowing from the sun, water, styling products, etc., and not to "dye" them with a purple shampoo like some older ladies do and end up with purple-blue hair... It removed most of the yellowing for me on the second wash and I expect to be fully satisfied in about a month. I don't want anything else, thank you very much.
P.S. It is obviously very strong and doesn't leave the hair soft, you need conditioner afterwards if you have long hair.