What was good and necessary about the Russian revolution?
To properly answer this question, it is essential to remember that the Russian Revolution really occurred in two major phases (three, if we consider the Civil War as separate.) The first stage was a reaction to the privations of the First World War, which only worsened living conditions faced by millions of Russian peasants and the newly-developed class of industrial workers. It also added to popular hatred for Czar Nicholas and his family. Facing staggering fuel costs and food shortages, as well as the loss of millions of Russian young men to a series of military disasters, the Russian people staged mass protests. When the czar's troops refused to fire on a mass of protestors in St. Petersburg, and thousands of troops joined the crowd, the czar abdicated the throne. In the face of such dreadful shortages, then, the Revolution seemed entirely necessary to the Russian people.
In reality, however, the provisional government established by the Duma after the Czar's abdication provided little in the way of necessary reform. The radical-led soviets, however, which were organizations of workers in Russian cities, promised reform, and they quickly gained the support of the Russian people, including the peasants. Perhaps the most important effect of the Bolshevik Revolution, which, led by Lenin, toppled the provisional government, was that it achieved the most necessary reform of all. It removed Russia from World War I.
Under Lenin, the Bolsheviks attempted to issue a host of reforms, particularly land reform for peasants. The Bolsheviks had promised "peace, land, and bread," all demands the peasants found essential to improving their condition. On the other hand, the revolution also ushered in a long, bloody civil war, but it paved the way for the rapid modernization under Josef Stalin, itself a staggeringly bloody process. In short, whether the revolution was good and necessary depends on which segments of society one looks at. Many Russians benefitted from education, health care, and other advances before World War II, but these advances came at the cost of millions of peasant lives.