Paper fiat currencies issued by Governments could work perfectly well, provided they used the money for the benefit of society.
IE, if they had the discipline of the Bitcoin code, we wouldn't need Bitcoin, the trouble is, Govts become corrupted, they are tempted to fund projects they can't afford or otherwise should not get involved in (wars) by printing money.
Printing money is a phrase we see bandied around a great deal, but if Govts only printed new money to pay for their pet projects, it wouldn't be so bad, what compounds the issue is that they BORROW this extra money from Private international Bankers who simply conjure the money out of thin air.
Taxes against the People are required to pay back this totally unnecessary Borrowing.
For more on this goto youtube and search 'Bill Still' 'the secrets of OZ' 'fiat money' 'fractional reserve lending'
More money in circulation means the money you have earned is devalued through inflation. Yes, you may still have $1000 in the Bank, but it's purchasing power is being devalued, it is becoming worth less because of all the extra money being printed (borrowed) and put into circulation.
Another problem with central control is the issue of Liberty, currently, as in the case of Julian Assange, the state can freeze your assets, switch off your access to banking.
This is potentially very sinister, do some research and you will see that totalitarian Govts often shut off access to money, food and water as a means of controlling large numbers of people.
Bitcoin addresses several of these important issues, firstly, it's a limited supply, whereas there is virtually unrestrained money printing going on, and there might even be new Gold and Silver deposits found, there will NEVER be more than 21 Million BTCs. These are divisible up to 8 Billion times so BTC has the potential to serve as a Global currency. There's no central control, Your Bitcoins cannot be blocked as they are sent person to person.
As people buy in, driving the price higher, instead of buying a meal for 1 BTC we will be using fractions of a BTC, a whole BTC becoming worth a considerable amount of money, this is called deflation, this is the opposite of what we have now with inflation devaluing our currency.
Pensions too could be transformed by this, simply work 20 to thirty years, buying BTC allowing them to deflate (increase in value) to a sizeable Nest egg, then retire when YOU want to.,
Currently, there's money pouring into Bitcoin, people say it's a speculative bubble that may eventually crash.
I believe though that Bitcoin is a Global asset, it is a peer to peer, anonymous version of Western Union, so if Bitcoin has no value then Western Union has no use to society either.
I think the thing that will determine bitcoin's ultimate success is if underneath the speculation, real industry and businesses can spring up using BTC.
For those early adopters who've gained, probably the best way to preserve those BTC Gains is to take 1% of your gains and help young BTC industries to flourish.