Bitcoin is definitely the future of currency. For online markets at least.
There is high volatility of bitcoin in exchange rates nowadays, but it is caused by still relatively small number of holders of BTC and merchants accpeting BTC. Though numbers are growing every day. However there is still long road to go and we're only at the beginning.
The stability of exchange rate can be achieved by enter of some big player or players into the BTC world. By that time the exchange rate should be somewhere 10mil$/BTC, or better to say 10000$/mBTC, or even better 10$/milliBTC.
I think this is also important for BTC to become widespread, to realise that amount of 1BTC is freaking huge amount of money (well will be in the future). And it would be better to switch to mBTC, or milliBTC eventually (when the exchange rate will grow to this level).
Lately I've bought just 0.1BTC. I told about it to my friends and most of them were jsut surprised, why so little?! They had absolutely no clue, that I actually bought a hell of a lot (for the future)
I'm not true believer, but more of a realist I would say