Just to clear things up a bit, I have mined bitcoins before about a year ago or so when the value was at around $30/btc. The concept is definitely very solid, the system is impossible to hack since there is no central computer (government) that controls it. Account values are constantly checked via P2P connections very similar to how torrents work. As for mining for bitcoins, you really do need a solid setup, if you use a common computer, you will never make any money, you would need full rack setups with very expensive GFX cards to do any heavy duty mining. I had actually quit mining for bitcoins because yes, the cost far exceeded the reward. The power cost alone was costing more and that didn't even include the initial hardware cost needed for the racks. Also, the way bitcoin mining worked, it would max out your rack's CPU and GFX card, so it would be running full blast 24/7, eventually causing your power supply to fail and other hardware related issues. Basically, it simply wasn't worth it at $30/btc. At the current value, it may be worth it, but no guarantee it'll stay that high. As far as transactions go, you need to be pretty tech savvy in order to even use bitcoins, which is why I don't think it'll ever fully catch on in the mainstream world. In fact, the reason bitcoins initially got so popular was because of the black market where people could send money in total anonymity and it's still one of the biggest uses of bitcoins.
Anyway, that's just my personal experience from it, hope it helped to clear some things up
