I've been using the Milani Liquif'eye Metallic Eyeliner in Black for several months and I can say that I'm thoroughly impressed by its pigmentation and staying power.
The left swatch is just from one stroke while the right swatch is from a few strokes. As you can see, the pigmentation is superb. This pencil is very black and I try to be careful when I apply this to my waterline (I only use it on my waterline or tightline) so it won't look too heavy or dramatic. This eyeliner is extremely creamy and glides smoothly. It lasted for around 4 hours on me in the heat and 5 hours in the cold before it started to show subtle smudges, which is great for my stubborn waterline. I would say by 8 hours, I definitely would need to have a cotton swab to clean up all the smudging that has happened under my eyes. Although there were some heavy smudging within 8 hours or so, my eyes still looked quite defined after I swiped away the residue. When I looked closely into the mirror, I could definitely see quite a bit of eyeliner left on my waterline.
Some have complained of sensitivity issues when putting this product on their eyes. The first couple of times I tried this product, my eyes did water and felt a little itchy in the beginning but after 15 minutes, the problem went away. Since then, I never had that problem.
Considering that nothing seems to ever stay on my waterline (except for a product that I will rave about soon in an upcoming blog post), I would definitely recommend this product to those looking for a good, dark eyeliner, especially for their waterline or tightline.