What is Karl Marx's argument against capitalism?

Marx's argument against capitalism is that it resulted in the creation of a class struggle between the owners and controllers of the means of production in society (the Bourgeoisie) and the mass of common laborers (the Proletariat) who were oppressed and exploited by the Bourgeoisie. Capitalism is designed to extract as much surplus value from the labor of the workers (profits) as it possibly can. In order to maximize profits capitalists force the Proletariat to work to a point where their lives, health and ability to enjoy life in general deteriorates.