The underlying theory may have been to create a paradise, and use dictatorial control to establish it, in the naïve hope that an established government would then voluntarily surrender power to anyone, much less to the "people". The ruthless actions to create that "paradise" quickly turned into a living hell (and a lot didn't live) for a significant number of those "people" he set out to help. The even more absurd notion that the country could run with just "laborers" and "the party" led to a near-total collapse of the economy, and rapid back-pedaling on several of those "It looked good on paper" ideas. If Lenin did indeed believe his own rhetoric, and truly thought that he was doing "the right thing", rather than using it as an excuse to grab absolute power, then I see him as a seriously misguided individual, rather than a monster.
The fundamental flaw with Communism is that once a society gets too large for peer pressure to maintain social equality and a "fair" distribution of both wealth and work (typically about 200-500 people, which works for a small hunter-gatherer tribe, but not for an urbanized industrial society), somebody has to decide who gets what, and whoever is in that position ends up with absolute power over those he decides for. At that point, there's no effective difference between that government and a dictatorship.
I'm left with one phrase to sum up the results: "What did you THINK would happen?"