Essentially any currency has to able to do only one thing, and that is the ability to be used to purchase. So yes the Bitcoin fits into that category. The only possible counter argument that I could perceive is that someone would oppose it as it is not linked to a specific economy. But the imaginary money in every currency system gives the same problem.
I love the fact that Bitcoins have no central authority, however there is a downside to that to. Bitcoins have a great purpose, but investors are taking advantage of its privacy and fluctuations, turning it into a market rather than a currency exchanged in markets. There is nothing legitimate supporting it; thus it could lose its value any day, and could have a massive negative impact on the economy.
I see it as a tool for the rich people to transfer their money to wherever they want without being traced, AND they could purchase anything with it, promoting crime.