Utility. It is the safest, simplest way to buy anything from anyone in the world.
I think this is a bit optimistic. Exchanging and managing bitcoins still requires the use of a computer and an internet connection, which makes it vulnerable compared to physical money from a established currency. Since it is still a very new currency there are also risks of the whole system crashing down due to unforeseen reasons.
However it's probably the easiest way to make anonymous payments.