Fair enough on the phrasing, but when I say "I believe", I mean to say that I reason that isthe truth but like to try to remain modest and not throw around very bold claims.

Anyways, solely by the fact that some people use it as a means of an exchange - Bitcoin is a viable medium of exchange.

Is it perfect? Is it great (considering current legal realities etc.)? Can it be used by everyone on the globe? Currently the answer to all three is "no", but it has a non-negligible chance to improve in all these aspects.