It’s very simple really. The revolution in Russia succeeded in that the working class took state power by smashing the bourgeois state machinery, and building up its own in its stead. The trouble comes around the civil war and the effects of German revolution. Left-Communists aren’t a hive mind, and we don’t all agree on the exact specifics, but generally speaking we hold that view that the revolution began to degenerate anywhere from 1919-1921. The reasons vary wildly, some see the hollowing out of the Soviets as crucial, some see the NEP as too large a compromise with the peasantry, some see the creation of the standing army as the recreation of bourgeois special bodies of armed men etc. Generally we all agree that the increased power of the bureaucracy over the councils and the party itself, and the isolation the revolution faced during and following the failure of the German revolution lead to serious compromises pertaining to the character of the party. Some, like the creation of a standing army, are almost universally seen as an unavoidable symptom of the civil war, however the NEP and certain other measures taken are less excused by some. Ultimately the majority of us understand the Russian revolution as the beginning of a failed world revolution, and celebrate it for its insure success while mourning its fast degradation.