I have tried MANY liquid liners and this is the one I have gone back to again and again!
The tip of the pen is super fine and allows you to choose to draw on a very fine line or you can make it as thick as you please as well. Also, the fact that it is in a pen (almost like a felt tip) makes application easier than having to paint it on with a brush - it gives you a steadier hand and therefore a much more clean and neat line. It lasts all day (or night) long, but is still easy to remove with a good eye makeup remover so you won't end up looking like a panda once you've wiped it off. Definitely a favorite for me!