I love NYX's extreme liquid liners so during a 40% off sale I snagged one of their crystal liners as an impulse buy. I chose the color Jade because it was just so pretty and really caught my eye. This product is basically a liquid glitter liner, sort of like Urban Decay's Heavy Metal liners but not quite as good. However they are much much less expensive.
Not intended for use around eye....watch out I'm about to be a first world anarchist.
I use this a lot either to enhance my regular liner or to add a bit of glam under my eye. Since this is not fully opaque it works great over eye shadows. I like putting green under my eye and then dabbing this on top to create a glitter effect.
As far as comparing it to UD's version, well it stays just as long but the formula does a very strange thing. Once it dries it gets sort of pulley...I don't know how else to describe it. You can feel it pull on your eye lid sometimes when you blink or look to the side. It isn't painful, just sort of annoying, especially if you are the type of person who hates to feel like they are wearing makeup.
If you can get over the weird formula this is a great affordable alternative to the Heavy Metal liners!
Where to buy: nyxcosmetics.com, ulta, drugstores