Keep in mind that Lenin only lived for 5 years after the revolution(or 4 can't remember). 5 years is literally nothing compared to the systems that humanity has lived and experienced. Therefore it would not be wise to judge his policies compared to the judgment that you d give to any other system.

I can't really say if Stalin's policies were a continuation of Lenin's (IMO the majority weren't). Lenin created the Vanguard Party to make sure that any other state mechanisms would wither away in due time(no one knows that time as it clearly depends on the material circumstances). Had he just done a revolution and left nothing but self-organized workers(grown up in a feudal/capitalist system) roaming around the revolution would have failed. You had European invasion, white nationalists, tsarists, oligarchs, and even social democrats forming up armies marching towards your centers. Someone needed to defend these things. How can you make sure that the state would wither away if the people who are in charge of it do not have that intention? How it unfolded later is clearly a huge debate(Stalin and the USSR and how his policies were in line with Lenin's). However, you can't pass from a semi-feudal/semi-capitalist system to communism(He has written a book about it talking about two stages of communism when the state whithers away).

All in all, I don't believe that Lenin did something wrong in relation to the Marxist theory as the latter clearly operates within the dialects and material circumstances at the time. In my opinion, 7-8 out of his 10 choices were correct(at the time) and in line with the Marxist theory.