I use Google Voice on my Droid X to call my daughter in Canada (no int'l cost, only minutes) and have never had a dropped call or static. Sounds just like a Verizon connected call to me.
I use Vonage with my Xfinity broadband service at home. Great sound quality, no lost calls. Only time I have a problem is if my cable is down I have to use my cell phone to call Xfinity to report it.