Biggest disadvantage of bitcoin is it cannot control by anyone and the main thing that i worries is every wallet is can be lost at anytime. Its only generated but not have ownership to anyone.
That is Bitcoin biggest advantage, it's decentralized so no government, bank or other third party entity can access your money. Not even secret services.
Bitcoin most biggest disadvantage at the moment is the fight going on and probably will keep going on in the future, companies trying to use bitcoin for self gain, now we have Blockstream, but in team nChain may do the same.
Bitcoin is for the people and should be controlled by the people..