Bitcoin is a cryptocurrency which means it is an alternate currency to our own. Bitcoin adds a new element to the world economy and it cant go through inflation. Bitcoin is supported by thousands of people "mining" for bitcoins. 1. Bitcoins unlike the federal currency are not backed by federal funding and banks to make it secure, instead they have separate people making it secure. 2. Bitcoin mining is where you make your computer do complicated math equations while you slowly rake it bitcoin profit by helping the security of the currency. By offering an incentive (bitcoins) for securing the currency they make people want to help, getting stronger by the day. Bitcoins are an economic revolution and their functions are useful and plentiful.
There is no reason why bitcoin shouldn't be legal. If people believe that an item, whether physical or virtual, has value, then they should be allowed to use it for trade. Currency does not need to be officially endorsed by a government. Gold, for example, evolved as a currency before any government decided to use it.
No, I do not think that Bitcoin should be legal and that each country or region should just keep on using their own currency. Bitcoin should just be used for online purposes only, and can make a decent investment tool, but I think most people like to be able to touch money.