I tend to avoid short stories and anthologies in general, but I picked this one up because it has some classics in it and is edited by Kingsley Amis, whom I had learned not long before stumbling on this book was a big defender of science fiction in a time and place when it was truly treated with disdain by the literary set. The introduction to this book is pretty aggressive. Amis goes after a few named critics specifically for their ignorant and snobby derision of the science fiction genre. So as a small artifact of the early literary history of science fiction, this was a nice find. The stories themselves were also quite good, though suffering (at least for me) from some of the lack of depth that comes with the form. The stories range from 1945 to 1960 by the following authors: Theodore Sturgeon (it was his Killdozer! that really drew me to buy the book; it's about a bulldozer that gets taken over by malevolent energy and starts killing everybody), J.G. Ballard (meh), Poul Anderson, Mark Rose, Peter Phillips, Murray Leinster, Alfred Bester (his Exploration Team was my favourite, about an illegal settler with a team of three uplifted kodiak bears and an eagle eking out survival on a deadly planet) and Arthur C. Clarke.
If you are interested in some of the best names of classical sci-fi and want to get a good sampling, I would definitely recommend you pick this up (or any of the other Spectra, I suspect, that Amis and Conquest edited). Good stuff.