It can theoretically be used as currency but also isn't that good of a medium-of-exchange or unit-of-account thus far.
If you have not already explored the Lightning Network, @edicted, then you may be pleasantly surprised. Set up a Lightning Node as a test and it seemed pretty easy. Saw a vid of a dude in El Salvador buying a few bananas with his BTC Mobile wallet over the Lightning Network. The LN uses atomic swaps. The same tech which Mr. Sun wanted to bring to the STEEM blockchain. It seemed very exciting to me in the early days of his arrival - but that's for another post at another time. ;)
From what I can tell the LN has a ton of technical issues on the backend.
I won't pretend to understand them but @brianoflondon absolutely does.
The biggest problem is that it's only good for tiny amounts and it expects everyone to run their own node or choose a custodian. Even in the best case scenario this makes Bitcoin a better medium of exchange but doesn't help the unit-of-account issue at all: which is the primary tenant of any currency: being able to measure value natively with the currency itself.