This is the only eyeliner I've used and currently still use, that doesn't smudge. I've tried many different brands and types of eyeliners out there Estee Lauder, Clinique, loreal, maybelline, almay, etc but i always always keep this one in my make up bag for everyday liner.
It can outlast just about any environment. Humid, rain, sweaty hot, cold, you name it. Under extremely hot conditions it can smudge a little over my eyelid if im not wearing eyeshadow but to combat that i just apply a little loose setting powder over it and my eyelid and voila no problems.
I have used this quite a few times and each time I was really disappointed, it just doesn't last. After a few hours it starts to run and is really smudgy under my eyes.. ends up looking like I have dark circles under my eyes. It's pigmented really well and is really dark and goes on nice and smoothly, just wish it would last and not end up all over my eyes!