So I picked one of these up a little while ago, and at first I was extremely satisfied with it. But then a few weeks in I noticed it seemed to die quicker and quicker. Then it stopped working with some carts. Now it doesn't charge at all. I even checked the charger with another pen and it works just fine.
I guess if you're in kind of a pinch it's okay for $20, but I'd probably spend a little more and get one that lasts a little longer. They make nice ones that enclose around the cart so you don't break it by accident for not very much more, which also use a standard android charger and support passthrough, so honestly Ooze isn't the way to go anyway.