The whitepaper says: A Peer-to-Peer Electronic Cash System so It's a digital currency and shouldn't be called otherwise even though people use it as an asset or something else.
If bitcoins is a digital currency why does it value always seem to raise, normally digital currencies should stay at the same value. To me i will liken bitcoin to Gold because it's value rises and fall depending on the mood of their investors and I'd say the same for silver, cocoa and other commodities.