The Communist Manifesto isn't just a great introduction to the doctrine of Marxism, it's also a great collection all the fun contradictions, inconsistencies, and fallacies that Marxist "philosophy" bulges with.
My problems with Communist/Socialist theory in general, and Marxism in particular are too many to list so let me just pose a few questions about the Manifesto that our more, let's say "egalitarian minded" scholars, might have a superior insight into.
1) If "Free Trade" is synonymous in the Communist mind with "exploitation" than what adjective do they associate with "collectivization" or "gulag"? How did a political movement determined to end the capitalist exploitation of labor rationalize the harsh treatment of the Russian peasant class following the October Revolution and Civil War?
2) For an ideology that stressed the transcendence of national political borders in the pursuit of a unified and worldwide workers revolution what do we make of the great deal of skepticism Marx and Engels have concerning not only globalization and international trade, but also the integration of "barbarian nations into civilization"? "Workers of the world unite, unless you happen to work in one of those barbaric parts of the world."?
3) How do we interpret Marx and Engels bizarre appeal to their readers religious sentiments when they criticize the bourgeoisie for drowning "the heavenly ecstasies of religious fervor... in the icy water of egotistical calculation"? That seems like a strange condemnation from ideologues who themselves ultimately sought to eradicate religion and replace church dogma with state dogma.