I have used it, actually. And I have a wallet with ~4.19 BTC... for which there's ~17.1 GiB of Bitcoin blockdata on my hard drive.
Not what I think of when I think of an easy way to transfer value, especially when coupled with the volatility of the medium. For trading small amounts of money with people in other countries, there are better ways, at least for the people I need to do that with - either using electronic checks (which are free, with my bank) or using the micropayments systems set up by cell providers in the portions of the world that aren't "industrialized"/1st world/whatever the term is.
Regarding what a Ponzi scheme is, maybe you should hit up Wikipedia (or where ever) and read the definition of a Ponzi scheme.. and then consider the history of BTCs. BitCoin might not be an Italian guy taking money for imaginary stamp transactions, sure... but an anonymous coder taking money for imaginary crypto transactions seems close enough that claiming it's something entirely different is splitting hairs. And lest we forget, the same person (or group) that mined block zero and thousands of subsequent blocks before releasing this to the open source community currently owns millions of BTCs. Last I checked a couple years ago, he/she/they had over 12% of all the Bitcoins that will ever exist... and you're seriously trying to say it's not a Ponzi scheme? How do you think the bubble's being inflated and the next round of investors is being paid off, if not by the money the previous round of investors put in, care of the inventor(s) and that multi-million BTC stockpile he/she/they built up? Think about it - sure sounds to me like an internet-age version of stamps scam that Ponzi ran.
If it was on the level, they would have done what the Litecoin did guy, and released (or re-released) the project after proving it worked, rather than only after securing a dominant ownership share. LiteCoins may share a lot of the same fundamental flaws as BitCoin (being a fork of the original project), and not be viable long-term, but at least I can trust LiteCoins. The guy who forked it mined 3 blocks before releasing it to the world, rather than being more concerned about getting a dominant ownership position in the market he was creating... so if I were to get behind any crypto-currency or digital currency at this stage in the game, it would be LiteCoins. It might (also) be a bubble, or doomed to failure, but at least it's not a scam by the inventor.