The status of bitcoin is not clear at the moment globally. Some countries treat it as commodity, some as currency. Some countries ban it. So it is not a global currency yet. But it is becoming one.
It is a global currency at the moment as well because you can use it if you want from any country if you have Internet connection. It's the acceptance that can make difference in the future if the merchants will start to accept it. In that case it can create a demand for it and it can help BTC to become a currency that's accepted worldwide.
That's partly right, sure you can use it from any country if you have the internet but if buying/selling of bitcoins in your country is illegal then there might be consequences if government finds out that you're trading bitcoins and even buy/sell itself becomes difficult and acceptance relies on that, if you're a merchant you are not going to start accepting a currency which is considered illegal by your government.