I switched from Tony Moly's Back Gel Eyeliner and Etude's Gel Pencil Eyeliner to this pen liner. It's truly becoming my holy grail eyeliner! This is the first time I've found an eyeliner that doesn't smudge at all! It stayed flawless from 6:30 AM to 9:30 PM without any smudging. The staying power seems unbeatable, and surprisingly, it's also easy to remove during cleansing. Although I haven't been using it for long, I think this will become a staple in my makeup routine.
First off, since it's a brush pen, you need to be careful when drawing your eyeliner. What's more, if you make a mistake, it's not easy to correct. You need to use a cotton swab with a bit of cleansing water or emulsion to wipe it off. Trying to erase it lightly with your fingertip doesn't work at all. It dries faster than you might expect after application. The long-lasting power might be due to the cold, dry weather and the lack of oil around my eyes. I'm not sure yet as I haven't used it for long, but we'll have to see how it performs in summer.
For those like me with oily eyelids, make sure to prep your eye area with shadow or powder before applying the eyeliner. I have hidden double eyelids that look like visible ones, and I have some fat on my eyelids. Plus, I need to use artificial tears due to dry eye syndrome. This eyeliner doesn't seem to smudge with water-based products like artificial tears, but it might be vulnerable to oil-based products like emulsions. So, I always apply a light eyeshadow widely around my eyes up to the outer corners, then add a point shadow before drawing my eyeliner. Although I'm a bit worried it might smudge in summer, it's been fine so far.