On my golden tan skin Cat O' Nine Tails comes off as a warm blackened brown with a hint of a bronze-wine undertone. Though it's described as sparkly it's more of a sheen on the skin. It's taken me a bit to figure out how to apply mineral liners well, but now that I have it'll be difficult to go back to gel/liquid liners considering the value and how little you need at a time. I haven't had a problem with fallout, but wear time and pigmentation could be better. I use Visine with this and not Meow's sealant, so can't say whether Meow's sealant would improve these issues.
I use this liner almost every day. It's similar to NARS' Night Fever, but the base is more of an espresso black/brown, instead of stark black. It goes well with a wide range of eyeshadow shades.
I find that the mineral liners don't last as well as regular pressed powder liners, so I recommend using a sealant to make sure your liner doesn't fade or slide away.
UPDATE: I find that Cat O'Nine Tails works best when applied over a brown pencil eyeliner like Milani Liquif'eye. The pencil base really brings out the color of Cat O'Nine Tails, and makes it seem less harsh...less of a dark espresso brown, and more of a complex, sparkly plum-bronze tone. The staying power is also improved when worn over a pencil. This is still one of my very favorite eyeliners.
A gorgeous, shimmery blackened-brown. I find that the longevity and color are at their maximum when the liner is used with a sealant (the one that Meow sells is excellent). In the pot, it looks like it would be a dark brown with cool undertones. To me, it translates to the lid as a warm black with gold and bronze shimmer. It is hard to tell that this isn't a true black unless if you swatch them side by side. Either way, I find this to be an interesting alternative to a straight up black liner. From now on, this will be a staple in my collection :)