I'll add that I think the USSR would have turned out pretty much the same without Stalin as well. Political opposition was banned and actively persecuted before he became really important, and most of the executive power was concentrated in a handful of offices- practicly an invitation for corrupt sociopaths.
Stalin lead the USSR to victory, but only after almost losing. If he hadn't purged the army and had reacted immediately when hearing of axis troops gathering at the border the Nazis probably wouldn't have been able to push so deeply into Russia to begin with.
Wether he was just as evil as Hitler is a moot question, really. I personally think that Hitler was crazy, especially towards the end, and probably thought that he was actually doing Germany a great service with his reign. I think that Stalin was ruthless to the extreme and paranoid, but otherwise completely rational.
Bookmarks