It's quite simple to use (assuming you have IPv6 connectivity) and worked very well in my testing. A big benefit to me was that Linphone lets you do direct computer-to-computer SIP calls, without requiring you to register with a SIP server or other IP-PBX. This gets around the need to have an IP-PBX that is IPv6-connected, which could be a different challenge.
As I noted in the blog post, I am definitely interested in any info people have about other softphones that support IPv6. Jitsi (the renamed "SIP Communicator") indicates that it has IPv6 support, but it requires registration with a SIP server, and I don't have one of those running on IPv6. If you have info about other softphones (or other VoIP endpoints), please do leave comments either here or on the other blog post. Thanks!
P.S. And yes, I'll be talking about and demo'ing Linphone in my IPv6 and SIP webinar on Thursday, May 5th.
If you found this post interesting or useful, please consider either: