Re: What do you think are the biggest disadvantages of Bitcoin?
Bitcoin is not completely implemented in every country and due to very low transaction fee many people are using for illegal activities, The price of bitcoin is also not stable. 
Well given the fact that bitcoin price is not stable, its all normal. I think the biggest hindrance to this is the high fee, slow transaction and the unsecured wallet. Everyone is complaining abou the transaction, like you'd pay a lot but still slow processing. Well I think right now we can't do anything about this, maybe wait for the activation of segwit2x.
As for me the biggest disadvantage looks like If your credit card is stolen or somebody hacks into your bank account there is a good chance you will not lose any money as banks will fix your balance. Even cash can be potentially recovered if the police acts fast. But with Bitcoin if you lose it you lost it for good. There is no mechanism to recover stolen or lost Bitcoins. If somebody hacks into your wallet where you store your Bitcoins you lost them for good. The best way to store your Bitcoins is on disk that is disconnected from the internet. 
The unsecured wallet is another to worry about but better be use offline wallet to this one. We're the one who's always responsible for our lose.