I've read and have been impressed with Dan Simmons' Hyperion Cantos and Carrion Comfort, and wanted to explore his short stories to see if they were up to his novel's quality.
Unfortunately, the short stories are mostly from his earlier years and aren't really up to the incredibly high standards he's set for himself with the Hyperion series, Carrion Comfort and other novels.
The stories are adequate, but none of them really stick in the mind after a while. If they were from any other author, I would say there "good" though not excellent, but knowing Simmons, I'd rate them as "just ok". Some of the stories seem to be more concerned with hammering the reader with the "message" rather than telling a good yarn. This is most evident when his rant (err, story) against televangelists. I agree with Simmons viewpoints, but didn't care much for the story.
However, this collection does offer some interesting glimpses into his novels. First, "Remembering Siri" is word for word, a chapter in his later Hyperion novel, and this is where it started. Second, "Carrion Comfort" is probably the best short story in the collection (and hence, the last story in the collection) and this forms the first chapter of Carrion Comfort, the novel. Again, this is where it started. Third, "Eyes I Dare Not Meet in Dreams" forms the basis of his later novel The Hollow Man, with exactly the same characters and premise. You can also see his fascination with the US space program in "Two Minutes Forty-Five Seconds", which was marred by getting the "message" across at the expense of storytelling. He explores the US space program from a different angle later on his novel Phases of Gravity. Lastly, there is a "story within a story" in "The Death of a Centaur" about a teacher telling kids a fantasy story. The story involves Raul (err, Raoul Endymion) guiding an unlikely band of characters to save the universe, battling the Shrike (yes the Shrike) and Wizards (err, The Pax) who are out to get them. The story is, well, standard fantasy fare, but it's interesting to note that he uses this story as a basis of his later Endymion novel.
So this collection is interesting if you're interested in "forensic" analysis of where some of his later great novels came from, but as storytelling tales in themselves, they're ok, not great. Having read both his novels and short stories, I recommend reading more of his novels before plunging into his weaker short stories.