12 years using Google Voice for our business. We don't normally see issues, but when the internet is choppy, sometimes we get an echo on the line. We use the call forwarding feature quite a bit and it forwards from the Google Voice number to one of our cell phones.
Receiving and making calls from the computer itself is possible, but we rarely use that method. Nearly always we pick it up on our cell phones and can then forward to another person if needed.
What kind of call quality issues are you seeing? You may want to contact them directly, and also run a speed test on your phone to verify that you're getting good data speeds from the locations you're in. My understanding with the Google Voice is that it's VoIP and would use the DATA connection on your phone, not necessarily the CALL connection - so that might affect things if you're connecting to "available WiFi locations" too as you'd be using their data connection and not your AT&T Tower.
