I don't use that much make up, only mascara and eyeliner. But that is the two things I swear by!!! I feel so naked without them.
I've tried hundreds of eyeliners but this one is my favourite so far. I also use the Cream Eyeliner from YSL, which I like as well - this one is just easier to carry around and I always have it with me.
It's so easy to make an even line with this baby and it never lets me down!

I've been wearing this eyeliner for a week now and I'm very happy with it - I have yet to see how long the tube lasts and how quickly it dries out but will report back on that one (I've had it when a pen lasts over a year so let's see if I get lucky here).
Easy to control/hold pen style (think marker/stylo/etc.) liquid eyeliner that delivers an intense black line - thin if you are using a light touch and thicker if you go over it or press harder (although I wouldn't advise that). I've created wings with it as well...it's very easy to use, nearly mistake proof and really delivers a solid, straight line. Also has staying power - definitely has lasted 12 hours w/o smudging, running, or causing raccoon eyes.
I've used Kat von D Tattoo Eyeliner Pen (color: Trooper) in the past as well as Stila's Waterproof eyeliner pen version (Black) and this holds easily as well as Kat von D's. Haven't tried it in /with water but it doesn't sell itself as waterproof. Still, for daily wear, definitely has good staying power for me.
I would definitely repurchase. Overall, very happy with the product. The only test now will be the test of time (how long the product goes w/o drying out).