yes, i have it installed and played with it. (I may even have already converted or compiled them for slitaz I think i tried them on slitaz)
I played with jitsi and linphone, i was more looking for a ip softphone than a replacement of Skype, though i know one of them (or both) claim to be skype replacements.
Both have been trouble to use, not handling connections or audio or both properly; one of them was worse than the other. I looked and asked for some hints on the internet, with no success.
They are far, far from being as mature as skype which works (almost) flawlessly, even on unix (though it lags the windows version), specially since the lates 4.x linux version last June. I am having some problems with it, but nowhere close than with jitsi or linphone.
I understand reasons for NOT using skype, but I see no real competition against it at this time.