I just got one maybe two months ago. I love the look and functionality but I don't use it much for Jubel, I'm actually using it for my foster dog now. It's too thin and Jubel pulls to hard when he lunges after critters. That doesn't happen THAT often but hurts when he pulls with the zumi lead, with a regular flat nylon mesh leash the force is spread out more on my wrist and doesn't hurt.
I'm trying to think of how I could add some padding or something to add bulk to the handle to rest on the back of my wrist so this doesn't happen. Not sure if I'll figure something out to work. Jubel's critter drive isn't going away, it's manages so that he only lunges after them when they pop up really close to us but that still happens too often for me to use the zumi with him full time. Foster pup actually flips out more over critters but he just doesn't have the strength to cause any issues for me on the zumi.