I read the 1979 DAW paper edition, which has a weak cover illustration, but a charming black and white drawing of one of the title creatures, accurately depicting its skeletal horse head, black hat and black cloak, opposite the title page.
I am a Vance skeptic. I often feel his novels lack plot and characterization, and that the cultures and situations he creates are totally unbelievable, not even internally consistent, and just exist as a frame on which Vance lovingly hangs his long baroque descriptions of clothes, food, and landscape, and a canvas on which Vance paints his unrelentingly cynical and pessimistic view of people and life. Vance, however, is highly regarded, including by people I greatly respect, like Gene Wolfe and Robert Silverberg, so I am still willing to give him a chance now and then. "The Pnume," the fourth of the "Tschai" books, is making me reconsider my harsh assessment of Vance.
Each novel in the Tschai series is better than the one before it, and "The Pnume" is the best Vance I have ever read, focusing more on character development and relationships. I recommend it, and am inspired by it to seek out some more Vance.