I wrote a review for the E.L.F liquid eyeliner in their regular line. I'm going to include it here as well because this is basically the same thing, and everything I said in that review is just as true for this one.
Only difference I want to point out is that this is slightly less watery compared to the one from the regular line, but I still find the end result to be pretty much exactly the same both in terms of application, result and smudging.
Here is the review:
This is horrible! It is so downright horrible that I'm kind of mad that E.L.F. has the audacity to sell this as a liquid liner.
This is watery. And when I say that I don't JUST mean that it's thin, poorly pigmented and runny, no it literally lays on top of the skin as a drop of water. It is impossible to use because once applied to the skin it slides around like a droplet of water and dries however it likes. And when it eventually does dry (which takes FOREVER), it dries to a very plastic-y finish that is not flattering at all. Also I have to say again that the pigmentation (in the black one at least) is so poor that it comes off as a light gray color, and because of consistency it is impossible to build on this after it dries.
Of course because this is basically tinted water it will also smudge like crazy even if you do by some miracle manage to get a decent application.
The only thing I like about this is that it has a brush applicator, which I might take out and try on other liners because it is very thin.
But over all, save your money because this is not even worth a penny. Actually I would not even accept this if I got it for free.
My current favorite in the liquid liner department is the Wet 'n wild Mega liner, and that one is not much more expensive than this, so I recommend trying that to see what liquid liner is supposed to feel/dry like on the skin.