I haven't dug too deep into it, but from what I've seen it seems complex, messy, and not up to solving real problems such as CJK Han unification. I wrote a bit about these difficulties in https://github.com/linebender/skribo/blob/master/docs/script... , and what I think was most disappointing is that I didn't get any actual feedback at the time. So it feels like about the same level of dysfunction as most Linux UI work.
