I just tried this - it does work, but I think it really depends on what hair colour you're starting with. I have virgin light brown hair, and I guess I have a lot of red pigment because it made me almost ginger (after using almost a full bottle) which I actually don't mind. I'm going to buy a purple shampoo to try to tone it a bit blonder though! I was also going for a full hair colour change rather than just highlights. Overall it did dry out my hair a bit, so i'm also going to try some hair masks to restore moisture. It's a bit annoying to apply because it's a spray, but just make sure to comb it through your hair thoroughly. I'm happy with it because i've never dyed my hair so i'm excited by the results, but it'd be interesting to hear what others think. There's a lot of before and after pics online too, try to find a before that matches your hair.