It's OK
Only tried on my upper lash line, not waterline. Goes on OK but I find that the blackness fades quite quickly, especially the flick at the outside edge of my top eyelid - possibly because it's waterbased? Product is very creamy and you have to take care not to overload the brush.
Aleph Beauty
There is great tutorial where Emma shares tips on how to line like a pro that could help ☺️
https://alephbeauty.com/products/gel-liner-onyx