Review (5/5): Awesome if you do a lot of outdoor/sweaty activities
I've been using this product for about five years. So very worth it.
I naturally have zero pigment in my eyebrows. I apply the dye once every ~4-6 weeks, and leave it on for 2 hours since dye does not take to my hair very easily. For more accurate results and less skin dying, I use an old mascara brush that I've cleaned off with rubbing alcohol - no vaseline needed. My eyebrows are also tattooed which I cannot recommend highly enough.
They say no eyelashes but I do mine very carefully with the mascara wand, again leaving on for about 2 hours. Between the dyed brows and lashes I don't usually wear makeup.
When you mix the tint with the developer, put the developer in the mixing cup first! If you do it the other way around, the air blown out by the developer bottle will blow some of your dye out, and it'll dye your bathroom sink in an instant.
Included a pic; forgive the grim face, it was taken just following the 2016 election.