Wolfe is rightly considered a master (if not THE master) of the science-fiction/fantasy novel, and yet I believe his greatest strength lies in writing short stories. This collection is his best. I've read collections by Borges, Tolstoy, Babel, Hemingway, Joyce, and on. This one tops them all, regardless of genre.
Wolfe's writing is a miracle to behold. His characterizations are always disarming, and his language is unparalleled. Other reviews have given some clue as to the stories in this collection, which are all speculative and challenging. Although the concept is now overused, this would be the one book I would take with me to the desert island to read for pure pleasure.