Today, due to relative low acceptance rate, it doesn't fulfill it's role as a medium of exchange anywhere near potential. Instead the largest amount of transactions is, as with regular money, people speculating on it's future value.
It's important to look not at what it's meant to be, not at what it is, but how it works out for people. Occam's razor applies rigorously, the way something works is how it works for you. Don't complicate it.
In the near future it can be used interchangeably with any currency. The question of whether or not it is one is therefore irrelevant. It will be the only currency-like to be safe, certain, quick and cheap all at once. Let's not argue syntax, let's argue semantics.