In the US here, made a few calls and seems like the call volume is a bit low. One call cut in and out on me where skype is otherwise stable. Also after ending a call the dial pad vanishes and you have to close it and re-open it to call out again. On a side note it would be nice to see this added to the Google Talk client.
I like Google and it's services, but they need to work out the bugs (as usual).
Let's hope it remains free for domestic calls (US and Canada) after 2010.
After reading this article, I went and logged into Gmail and was presented with the feature, I installed it and tried it out, pretty darn good. I'm in Canada, so its not only US. And I will enjoy making free calls to Canada and the US, well until the end of this year.