At the time I write this review, A Small Killing has an overall customer rating of 2.5 stars - surprisingly low, both for an Alan Moore book and for a book that won the Eisner award in 1994 for best graphic novel. If I had to guess, I would say this has the lowest review for any Alan Moore book on Amazon. Presumably, the people who gave this a low review got something they were not expecting. If you're familiar with Alan Moore from his American-style action/adventure/superhero works (Watchmen, V for Vendetta, LXG, Tom Strong, etc.) be forewarned that this book is absolutely nothing like what you're expecting.
A Small Killing is a completely psychological story told through metaphor and heavy-handed symbolism. It is an exploration of one man's inner guilt and feelings of failure told through memories dating to his childhood. There is almost no action, heroes or villains to speak of. Rather, it a journey backwards in time through the life an English-born 1980s Yuppie working in the advertising industry in NYC. Themes explored include loss of innocence, the malleability of memory, denial, and guilt. There is also some minor commentary on capitalism and consumer-culture. I was not a fan of the art, which looks to me like blurry watercolor paintings done by a child. However, it is adequate to tell the story.
I strongly recommend this book to anyone who is a fan of European-style graphic novels, or some of the American adult-themed nonfiction books. The beginning is a little rough as you try to piece together the plot (which again, in many ways is told in reverse chronology.) However, about halfway through all the pieces fall into place and the book really picks up. By the end, I was turning the pages with anticipation as fast any action/superhero comic.