This product is so innovative. It's a gel auto eyeliner. Twist the pen at its end to push the gel out of the rubbery slant tip. However if you over twist you will see a chuck of gel oozing out of the tip. My take is twist till you hear one or two clicks for thin eyeline and two to three clicks for thicker eyeline.
I do throw away gel liners in jars as they do dry out and I find that revving the creaminess of that becomes a hassle. For this, it ensures that you will get the same creaminess as the first time you used it as the only opening is small, preventing the content in the pen to be exposed to the air.
As for drawing straight or curve line, this is really good to work with as the tip is firm and flexible. For me, it is much easier to work with than a brush, where sometimes the thickness of the line change when you preside too hard against eye. This gel pen does ensure a consistent thickness of the line drawn.
The quality of the gel is good. It's really matte and colour intensity is great. It does not smudge and is long lasting.
I think it's worth its price, $21.90, for the convenience and the quality it brings. I just wonder how long it will last. I wish they could manufacture the same product in a clear pen tube so I could tell how much was left. I will rate this 5 out of 5 and am sure will continue using it.