The only main disadvantage of the bitcoin is not accepted worldwide. As of now few countries accepting and when its accepted by all over the world then nothing is stopping this bitcoin.
We should not be as impatient when it comes to bitcoin, adoption takes a lot of time, we will probably need another 20 years before we can see if bitcoin is going to be accepted worldwide or not, I know that is a long time for many but it is in fact a small amount of time when viewed in historical terms.