Probably no name turns off more Americans than "Marx". That's unfortunate, because the 20th century communism associated with Karl Marx is not really a fair representation of Marx's ideas. Not that Marx wasn't wrong on a number of key issues, such as thinking that eliminating private property would produce true individual freedom. But Marx didn't have much use for government, so it's ironic that he's associated with a Leninist-Stalinist model that attempted to put all aspects of life under government control.
Besides Marx the political revolutionary who felt compelled to correct the dreadful condition of the 19th century working class, there's the Marx who's regarded as one of the founders of sociology. "Consciousness does not determine life, but life determines consciousness." (C.f. the then-current Enlightenment view that every decision we make can be as rational as we want it to be, and thus every individual is responsible for his own state in life.)
But on to the review. There's a ton of books about Marx available, as well as pounds of Marx's own writings, so why read this book? Because Prof Singer has written a very readable, very understandable description of Marx's thinking: contradictions, mistakes, and all. And done it concisely.
Prof Singer is sympathetic to Marx the philosopher -- no philosopher ever gets it all right -- and less sympathetic to Marx the economist and "scientific historian". But Singer presents it all in a very well organized fashion, with lots of references to Marx's writings, so that the reader can easily follow along with the main ideas as well as continue on his own.
Personally, I think Singer is too harsh towards Marx the economist, e.g. Marx's prediction that a capitalist system must eventually collapse. Whereas Marx recognized that government would side with the ruling class, i.e., the capitalists, he couldn't have predicted that government would grow powerful enough to bail out the economic system whenever it was near collapse. I doubt if any 19th century economist could have guessed that. Marx also failed to note, as Karl Polanyi did much later, that the general public would require government to restrict the worst activities of the capitalists, e.g. child labor, monopolies, pollution, near-zero wage rates. And this would make society more livable for workers -- thus postponing, perhaps permanently, capitalism's end. Singer, interestingly, shows that Marx may have overstated his case intentionally at times, in order to have more effect. We can certainly see that among modern writers, who know that the more extreme the statements they make, the more attention they get and the more books they sell.
Despite the things that Marx got wrong, he got many things right: the boom-bust cycle of capitalism, the alienation of factory workers from their work, the need for capitalists to find ever- wider markets, the growing disparity (though irregular) of income between capitalists and workers, the concentration of economic power into fewer and fewer hands, the influence of someone's economic situation upon the decisions he makes.... A basic knowledge of Marx is really a prerequisite for understanding many of the issues and conflicts that we still deal with today. Prof Singer's book provides that introduction in the most easily-digestible form that I've seen.