First of all, I didn't purchase this in the classic black, but in a shimmery khaki green that appeared in stores lately. I've also seen it in yellow gold and electric blue, however at least the one I got doesn't have a shade name on it. So, I cannot comment on the intensity of the black one, which I'm sure many are interested about, but I assume everything else about my experience applies to the rest of the shades, as the brush and the formula are probably the same.
So, the brush..... Where do I begin with this brush. To be fair, I'm not very skilled with non-pencil eyeliner and I've only started working with it and trying to get the hang of it for the past twelve months or so. But this one definitely does not make application easy at all. It's thin, laughably flimsy and too long. Therefore it's difficult to control and get very close to your lash line. I keep accidentally getting product on my lashes. Also, getting a smooth, straight line is a struggle and don't get me started on getting both flicks even.
In addition to that, correcting any mistakes is a struggle in itself, because this shade has a ton of glitter; the pigment can be removed pretty easily, but the glitter tends to stay behind, stick on the skin and make a mess.
Now, for the consistency, it's pretty ok, as I mentioned it has tons of glitter but I don't mind that, it was pretty clear when I chose it anyway. It goes on quite light and not so visible, but once it dries it darkens and it sets into a shade that really does pop. It compliments hazel eyes beautifully, I must say.
So all in all, for three euros I don't regret this purchase at all. I wouldn't buy it again though and I would never dare go anywhere near the black one. In my opinion, it's a nice thing to get if you're looking to experiment with fun colors, but I would never recommend this for a classic, black eyeliner. Tons of much better stuff out there for that.