If by the "far-left" you mean democratic socialism, then yes I think that far-left ideology does lead to a better society.
Currently, under capitalism, major economic decisions are made mostly by large companies who (especially since the decline of organized labor here in the States) have no democratic accountability whatsoever to their workers or to the greater community. An economic system which places democratic control and popular need before profit would be a much saner alternative to the market anarchy and private centralization of power which exists within capitalism.
And there have been plenty of examples which support this conclusion. The Mondragon Corporation in the Basque country is the fourth largest corporation in Spain- and is a cooperative owned by the workers within the company. Building societies in England and credit unions in the States have provided much needed financial support and democratic control in times of need. Even within social corporatism and the mild social democracy that is practiced in Germany, co-determination (a system by which boards of directors are half-elected by workers in companies with over a thousand employees) continues to be a positive force for German workers.
So many politicians have proved to be successful from Julius Caesar to Vladmir Putin. The problem is finding the best leader for your country no matter the party. Politics have always been corrupt. What you must notice is that every single type of government sounds perfect on paper. It is much harder to do than it is to hear. Politicians generally try to find away around it.
Far left economic principles is essentially socialism, the redistribution of wealth, and the government controlling your life. While I agree with the liberal ideals of personal choice and freedom, I do not agree with social restrictions and the loss of control that big government brings. I think the people should be fiscally responsible, and that we know what's best for our lives.