I bought this bottle of magic for the first time almost two years ago when I went into Sephora for the first time.  Mainly, the genie-like packaging was the thing that drew me in and encouraged me to shell out almost twenty dollars for it.  It was definately worth it.  This is my first primer so I don't know what I could compare it to... But it's amazing.  The first time I used it, I was amazed that my cheap eyeshadow was still on by the end of the day.  It keeps shadow on for hours [mine literally doesn't budge until I take some eye makeup remover to it], your shadow doesnt crease, and it prevents fallout.  The only con is that this gorgeous bottle snags some of the primer, but you can soak the container in a mug of warm water and all of the primer will melt off.
I can't wait to get Sin. (: