I have it. I requested an invite on the website and received one about a week ago. You can call anywhere in the U.S. and Canada for free with your land line or mobile phone. Once you choose a phone number,you set that up with your home or mobile phone. When you make a call through your Google Voice number it connects you to the phone you chose. So when I make a call through Google,my home phone will ring and it connects me to Google voice and then it calls the number I dialed on Google and call is free. You can also text anyone in the world for free.
I don't feel any controversy about it.
There are other things you can do with it to that I haven't set up yet. You can record a special voice mail for any incoming number you choose and as many as you want to. So I could put a private voice mail for my girlfriends number!

You can block numbers too.
And you can pre pay to call around the world and its very cheap. Some countries are only 2 cents a minute.