Its not accepted globally, and the value price can not be predicted its up and down..price not stable. So if you are not careful you lost all of your bitcoin due to exchange and its up and down value...
You are right about it is not accepted globally but i dont agree with you on the second point you mentioned that unstable price of bitcoin is a problem and someone can lose all bitcoin if not careful, but i dont think anyone would lose any bitcoin because of unstable price because if you are using bitcoin everyday then you will always know the price as it does not just jump from $600 to $0, you will always have time to sell your coins.
Unstable prices bitcoin is an attraction for all trader and if the price is stable surely you will never get profit by increased price.