In this memoir, Arthur C. Clarke describes the early days of science fiction, when he as a schoolboy in England thrived on the sci-fi pulp magazine Astounding Stories. Later he would contribute stories to this magazine, as would most of the other greats in the world of sci-fi: Isaac Asimov, Robert A. Heinlein, H. P. Lovecraft, to name but a few.
Astounding Days is divided into three parts, describing in short chapters the development of the magazine under its three first editors: Harry Bates, F. Orlin Tremaine and John W. Campbell, Jr. There's also an epilogue, containing among other things a reprint of Clarke's short-story "The Steam-Powered Word-Processor," and an appendix with a listing of Clarke's contributions to Astounding Stories (nowadays Analog), and reprints of some of his letters to the magazine.
Clarke writes with his usual elegance and gentle wit, and offers some insights into the early development of his career. There are some interesting and amusing anecdotes, but mostly he comments on the contents of Astounding Stories during the 1930s and 1940s. The visions of the future laid out in its pages had a profound impact on Clarke, and came to play a significant part in directing the course his later life would take.
Astounding Days is an interesting and entertaining book, easy to read and often captivating. But you do have to be a fan of sci-fi in general and Arthur C. Clarke in particular to get the full enjoyment from this book. From that point of view, it's highly recommended.