I have read it today, for the first time. I am passingly familiar with some of the theories of communism, having debated quite a bit with a number of leftist anarchists, and had a lecture on Marxism crammed down my throat at high school (thanks Mr. Whipple!)
I am somewhat unimpressed. The argument depends on the existence of conflict between the proletariat and the capitalists, and that industrial economies will erode all distinctions in society until we get to the point where only these two classes exist. The reason these classes exist is because they are the two inputs into production (labor and capital). As anyone can tell you, this is a bit simplistic: there are many different types of labor and capital, which leads to many different classes, all fighting each other for a piece of the pie.