I was a little excited to see this book at the library. I have been getting more and more into Barth, even though I'm Catholic and he is quite polemical against the RCC (in sincere, theological opposition, I think.) Here, Kung says exactly what I feel had been at the back of my mind, but could never articulate myself.
What made things tedious for me were the copious amount of quotes. One-third of the book, maybe...? Running through those citations made for a slow, jumpy read.