Personally, it's my favorite. I used to be a pencil girl so it's really easy for me to use. I like the variety of sizes she has in her Triple Threat pack too. It lasts all day long for me and I havn't had a problem with bleeding or smudging because it dries pretty fast.
I agree with apocalyptica the KVD tattoo eyeliner pen has great pigment and coloring once you put it on, it's especially nice if you wear more colored or darker shaded eyeshadows because it still appears on the skin. So easy to hold and apply, its one of my own personal makeup staples!