When I ran out of my Revlon Colorstay Eyeliner, which has been my favourite basic black eyeliner to date, I decided I would try something new. I bought the Maybelline New York Unstoppable waterproof eyeliner in the colour Onyx to replace it.
This is a twist-up kohl eyeliner, which is usually my choice of eyeliner because application is easy and they are usually better quality than regular pencils. Not always, but usually. This eyeliner is a very nice dark shade of creamy black. It creates a very nice dramatic look on the eyes. Ignore my bare lashes, I didn't want to hide what the eyeliner really looked like by using a bunch of mascara - but the overall effect is definitely better when you do wear mascara.
As far as being waterproof, it lives up to its name. This is what the swatch looked like on my arm after scrubbing with soap and water. A little bit of water definitely wouldn't have changed the appearance of it at all.
I would definitely say you're safe from streaks and whatnot, even if you're caught in a rainstorm. However, just because something is water-proof doesn't mean it's smudge-proof. This eyeliner smudges VERY easily. This is nice when you want to smudge out your eyeliner to make a smokey eye, or anything else. It also makes application more difficult, though. I often end up with smudged out corners when I don't want them. It also doesn't stand the test of time against oily eyelids. And I have very oily eyelids. Even when I use a good eye primer, like Urban Decay's Eye Primer Potion, I often have a black line through my lid from my eyeliner half way through the day.
As far as eyeliners go, this one isn't the worst, but it isn't the best. I wouldn't repurchase, but I will probably use it until it runs out.