Corn ethanol cannot provide fuel in a sustainable manner, and its production and encouragement as a fuel source only serves to cause an increase in food prices around the world. Ethanol would not be viable in the slightest, or as widely (if you can say that) adopted as it is without government subsidies.
Corn ethanol is definitely a controversial and ineffient way of producing fuel. First of all, it involves a lot of energy just separating the corn in order to use the glucose for biofuels. Secondly, by using so much corn, you are driving up the price of food on the market and animal feed.