Despite the bad ratings, I actually enjoyed this product.
For reference, I have eyelids that are slightly oily and prone to creasing. My eyes get quite watery at times, and I have a bad habit of rubbing them.
I have this eyeliner in the color Beyond Brown. From what I've heard, they've reformulated it from the old black liner so that it would be more creamy and easy to use.
Packaging-wise, I find it convenient to use since it's in a pen format, and it makes both my morning routine and traveling with it much easier than having to use and wash a brush when using a gel liner in a pot. However, at the same time, I feel like you're wasting product whenever you use it, as you have to twist up and remove the topmost bit of liner from the last time you used it, which has since dried up. For such an expensive product, I'd like to be able to get my money's worth out of it. :(
Formula-wise, the texture of the liner is creamy and ever so slightly thick. It's very pigmented and is a nice, neutral dark brown color. It applies smoothly and doesn't drag or skip. However, it does take some getting used to, and patience. You do have to adjust a bit to be able to use this eyeliner properly. Best of all for me, it says all day and looks great all day. I don't need to worry about it fading or smudging, which is very convenient. This is the main reason I like this eyeliner so much. Also, it is removed relatively easily with a makeup wipe, so no fuss there.
All in all, this eyeliner would be good for someone who is willing to dish out the money and wants a great-looking line that stays all day. The biggest negative is that you're disposing of quite a bit of product in the process of using, which keeps me from giving this eyeliner five stars. However, if you're willing to look past that, I find that the innovative packaging and great formula really make this product shine.