Yeah, well, I'm 'on it' - I think it came with some software I downloaded. But I don't know anyone else that uses it so it hasn't been much use so far.....
I'm on Skype too. Have got most of the family on it now both in the UK and some of them abroad. Works much better on broadband, have used it with dial-up to call Pakistan, get usable call quality and that was with MSN Messenger with Webcam sharing too!
Also installed it on my PDA (XDA IIs) - call quality on that suffers with a bit of a time lapse, not much use to be honest but I love playing with this sort of thing
Tried it years ago, but found that telediscount was of similar value for international calls and much much more practical plus I have a company mobile which is paid for, so national calls are covered too.
Skype certainly seem the one to go for as they have got it pretty much nailed.