These stories are brilliant. I had read those that had been published in Cosmicomics and Time and the Hunter before but I was really pleased to get this complete volume as a gift. First, there are over 100 pages of new stories (at least new in English translation) which account for over one third of the book. Secondly the print quality is vastly superior to the Picador paperbacks I had, which are now yellowing with age but were also rather blurrily printed in the first place. Thirdly, it is an attractive book and it's nice to have a hardback of a book you love. And finally, reading these stories again after almost twenty years has been great fun.
They are narrated by a character called Qfwfq who has been present in some form or other throughout all time: "All at one point" is set before the big bang, in "Games Without End" he and a friend play marbles with newly formed hydrogen atoms, he is a dinosaur and one of the first aquatic animals to leave the sea, he was present on the earth as its atmosphere formed making it possible to perceive colours, and so on. I wouldn't call them science fiction, rather they are fiction that uses a scientific idea as a starting point. I would strong disagree with hurricanheidi's review - I think the first story, "The Distance of the Moon", is anything but silly - it reminds me a bit of Borges and Garcia Marquez - it is funny and touching. But, to be fair, don't read these stories if you like your fiction straight and rational.
As a narrator Qfwfq is endearing, funny, slightly self important, and a bit of a know-it-all. He is also regularly in love with some ever so slightly unattainable vision of female perfection. If you have read Calvino before these stories are full of the usual wit and whimsy you expect from him. If you liked The Castle of Crossed Destinies or the Marcovaldo stories, you should love these. If you haven't read him before then these stories, or either of the two books I mentioned, are a good place to start.