I had 10BTC quite some time ago that I got for about $3 each, and lost it when the site my wallet was on was "hacked". Now I can't remember the name of the site. It was just a curiosity at the time.

A few months ago, when the mining reward halved, I thought it might be a good idea to get back in, and bought a few dozen through http://coinbase.com at ~$13. That worked out to be a good investment.

I'm uncertain about the future of bitcoin. However, IMO when the Chinese pick it up in earnest, it could get crazy. The ability to move money without government oversight is a real need for a lot of people. For that reason alone I decided it was worth having some.

BTW, I don't think it matters if it is a currency.

EDIT: If you look at blockchain.info, about 70% of the transactions are SatoshiDice. Gambling has been the biggest shot in the arm to Bitcoin yet. However, it's not just SatoshiDice bringing growth.