I've not done any mining or own any - but quite a few of my friends have, and they seem to have done pretty well out of it (at least, if they cashed in).
I'm also of the opinion that this is a huuuuuuuuge bubble ("greater fool theory" and all that). Great for anyone that got in at the right time and cashes out, particularly the way things are at the moment. However, there are going to be a lot of burnt fingers.
I was at the pub on Weds night and everyone at our table had recently invested in crypto-currencies (most within the last week). All of them had made substantial profit gains (on a modest sum though). I think they all expected the bubble to burst, but found it a bit of fun.
Bitcoin has some great technology for currency of the future, but there are some huge problems with using it as an actual currency. The fact that people are investing in a currency that has no backing, just perceived value, rings alarm bells for me
. I can't imagine it not crashing.
I'd be cashing out immediately if I owned any (but I said the same thing a year ago when it was worth much less, as I'm frequently reminded by my friends!).