The pros of totalitarianism, as with any dictatorship, derive from the strength of the state and its ability to take action promptly and advance its own interests. The primary con is that individual freedoms are nonexistent, and all human interests are subordinated to the state.
Because no opposition to or criticism of the government is allowed in a totalitarian state, relative stability is possible. Additionally, because decisions are made in a strictly top-down manner, with no mediation by elected bodies, large bureaucracies or otherwise independent entities, actual policy implementation usually follows quickly after decisions are made. Totalitarian regimes also tend to install competent people in key positions to make the execution of policy even more efficient.
However, the strict exclusion of the populace from any decision-making arms the state with complete and consistent recourse to the instruments of coercion, namely the armed forces and police. Additionally, totalitarian states have historically revealed themselves to be hyper aggressive, nurturing policies of expansionism and militarism towards neighbors and thereby exposing their citizens to almost ceaseless war. Furthermore, because people living under totalitarian regimes have no political voice, they may either engage in dangerous, potentially subversive behaviors or, alternatively, become neutralized, complacent and dispirited. All of these characteristics are exemplified by the fascist dictatorships of Mussolini's Italy and Nazi Germany in the 20th century, each of which eventually succumbed catastrophically due to its own brutality.