I am using them as both currency and investment. I'm holding a few btcs, it is a good long term investment opportunity which will be digital asset in future once its value may be considerably increased.. As currency I pay for some services like transfer of money, gambling and some digital goods and services.
Me too I am using bitcoin as both, currency because I am using it for paying merchants and websites for having their services.
And with the investments, I do invest my bitcoin with trading and buying the alt coins that I think that is going to have good future and value.
And the rest, I am just holding it and waiting for price increase.