I'm always astounded by comparisons of bitcoin to paper cash - in 10 years we probably won't even be using paper cash and it is hardly ever used for large transactions now in advanced countries - paper cash is history. I think I've done about 5% at most of my spending in paper in the last month.
How about digital cash?
Also, Bitcoin can be confiscated by the government, along with the computer/server it sits on (see silk road). A $5 wrench or a jail cell will deal with your encryption. You can also permanently lose it if someone copies your wallet/backup and then spends it particularly while it is on one of these exchanges - that's because transactions are not reversible or traceable to a verified identity.
Technically, I think Bitcoin sounds really substantial and love the idea of creating/spending keys which avoid government inflation, but the axioms on which the usage is based are all wrong -
I've never lost money in a fire, and never will. I don't want to avoid government confiscation by technical means (which fail), I want to avoid it by law. I don't want to be able to launder money (or for others to). I don't want my transactions to be anonymous and to have no central authority and no accountability when theft/fraud happens.