FF. Lenin was not the problem. The idea wasn't the problem. The corruptibility of the idea, and such, as taken advantage of - by Stalin - was the problem.
The idea itself is quack pseudo-science.
The idea that you can eliminate class based divisions and then just flip a switch to having no gov't at all is completely out of touch with the reality that is human nature. In the latter sense it makes the mistake of all anarchists in presuming that such wouldn't melt down into anarchy and lead to the people rallying around the first strong man on a horse who rides in to save the day.
In the former, it fails to account for the fact that humans are flawed and easily corruptable, meaning once empowered through the process that is suppose to remove class based divisions, the Communist elite will move to preserve its own power and thus never completing the cycle anyway.
It is the perfect illustration of an analysis expressed in the simple language of a Mexican bandit in the Sergio Leone western, "Duck! You Sucker" set in the Mexican Revolution. "The people who read the books, they go to the people who don't read and tell them it is time to make a change, so the poor people make the change. Then all the people who read the books, they sit around their big polished table, and talk and talk and talk, and eat and eat and eat, meanwhile what has happened to the poor people? They're dead! That's your Revolution! And then you know what happens, the same fing thing starts all over again.
There never has, and there never will be a successful Communist Revolution, because Communism doesn't account for the flawed nature of humanity. Lenin was the first example of human nature corrupting the process. These people were terrorist thugs and killers, who but for the complex nature of the events surrounding the last Tsar and World War I, would have never found their way into power.