I think that the biggest disadvantage of Bitcoin that all of the old-fashioned people so used to use "candy wreppers" - fiat money, they can't understand another system. Government will not be satisfied because it'll be hard to take charge, and to control people and it is disadvantage to mainstream too. But of course it is "disadvantage" only to popularize bitcoin, so for people who understand it is of course very big advantage and the main idea of it!