Biggest disadvantage of Bitcoin for me is rates are still very volatile. and has no legal force.
But for online payments, bitcoin be one solution. besides perfectmoney, paypal or others.
The reason why bitcoin has reached this place today is because of that volatility and you are saying that it is one of the disadvantages of bitcoin, i really don't agree with that. People are earning money through this, world is being curious because of that then how come it can be a disadvantage?