Review (5/5): Worked perfectly for me!
I purchased two kits, the Lusty Lavender and the Blue Envy, intending to dye blue and purple streaks into my hair. I probably should have known that I couldn't get streaks without foils, but that's my own failing. Other than that, though, the kits worked much better than I was expecting.
My hair is naturally a fairly light ash blonde, and it was highlighted a long time ago and never grew out, so I really only bleached it so the color would take well. I was surprised at the results of the bleach -- it pulled my hair to a lovely golden blonde that I might go back to after my color's faded out. It was strong, and the fumes didn't feel great on my eyes, but overall, that part of the kit wasn't lacking in the slightest.
The next day, I attempted to put in the purple and blue streaks. However, I didn't use enough dye, and I didn't leave them in for long enough, so they weren't dark enough for my liking. In addition, since I was doing it in stages, and I'd done two applications of bleach, I didn't have any gloves left to do the dyeing. DO NOT MAKE THAT MISTAKE. My hands were stained black, and the only things that made a significant dent in the color were nail polish remover and Veet hair remover. Wait until you have gloves. It was a horrendous mistake.
The color after the first application was more pink and cornflower blue, which wasn't exactly what I was looking for, so I went back and thoroughly dyed all of my hair but an inch or two at the top. I let it sit for about two hours, and then went to rinse it out -- a process which took nothing short of eternity. Two days after, I'm still rinsing out purple, but I expected that.
Once I finished the second application, I wound up with a very rich, dark, even, and dimensional color that's a mix of purple, blue, and indigo, lighter in some places, darker in others, which I think looks much more 'natural'. Great kit, although I do think they should include two pairs of gloves for people who dye their hair over two days.