It's very good, but I think the problem is "too many parameters." In some contexts that's fine (animators are used to it) but in others it might not be ideal. People don't use that spline for font design work; why? The Hobby spline has a tension parameter, which is said to be "very useful" in the paper, but when Apple adapted it for Pages, they left it out of the UI. Was that a mistake, or did they make an informed user experience tradeoff? (Incidentally, I believe tension is in there, as part of the illusion of extensibility, but deeply hidden)

So whether this spline is better for, say, animation, is what I consider a fascinating research question. Hopefully putting it out there will start to get answers.