Anthologies are notoriously inconsistent. Most contain several essays considerably below the level of the best pieces and many contain a few utterly miserable ones. On the downside, no essay in this collection truly stands out; on the upside, there really isn't a weak entry in the volume. I honestly cannot think of another collection of which I can make that statement.
Whether you are a serious fan of Sci-fi or a casual reader seeking an introduction to the field, this collection will prove invaluable. I fall somewhere between those two categories. Over the years I've read a few hundred Sci-fi novels and seen most Sci-fi films that have been made, but it has never been my main source of reading or film viewing. I've read rather a lot of the historically important works such as Mary Shelly, Henry Kuttner, H. G. Wells, Olaf Stapleton, and David Lindsay, but I've never attempted anything like a comprehensive reading of the classics. And I have ready very little that has been published in the past fifteen years. Still, I found that I learned an enormous amount about the field from this book. I learned about several historical works I had not previously known of, got a better understanding of the state of the genre from one decade to another, and learned a great deal about trends in the field in the past couple of decades. I also learned something about the various literary critical reactions to the genre. For those in the academy, it is a helpful introduction to the scholarly take on things.
The book is also great at pointing the way to other books. I kept a sheet of paper beside me as I read. I have already bought a few critical books on Sci-fi based on mentions of them in this volume, while I also have compiled a list of a number of novels that I plan on reading.
The essays in the book are broken down into three separate sections. The first section deals with the history of Sci-fi, from precursor works to the magazine age to various decades after. The second and most academic section deals with various academic approaches to Sci-fi, including Marxist, feminist, postmodernist, and queer theory. The final and most wide-ranging section covers a variety of themes such as gender, race, hard science fiction, alternate history, space opera, film and TV, and religion. The writers are mainly English and mostly academic, though several are also writers of Sci-fi. Even the writers, however, are fully qualified academics. For instance, one of the more scholarly entries is that by Brian Stableford. Though most of the essayists are British, American Sci-fi has so completely dominated the genre that it automatically demands priority. If anything, I was somewhat surprised by the absence of some European writers. There is, for instance, very little discussion of Stanislaw Lem, though several deserving British writers do receive attention.
In addition to the very good essays there is also a very interesting (though certainly not exhaustive) list of chronology listing some significant novels, short stories, movies, and television series. There is also a good bibliography at the end of the book, though I wish it had been annotated.
I highly recommend this collection to anyone interested in Sci-fi either in a casual or more dedicated fashion. In all honestly I have to say it is one of the most successful volumes in the Cambridge Companions series that I have read.