GV is horrible. The quality of your phone call goes down too much. I would only give it to a few people and try it out for yourself before telling everyone that your number has changed.
Not to mention, that if you are a verizon customer, that GV texts and calls are no longer in Network minutes and you could have a large bill if your account is not set up correctly.
For the record, neither my wife, myself, nor anyone we talk to have any complaints about the call quality, and we're full-time inbound and outbound GV users now. We both consider call-quality to be great (unlike the speech recognition accuracy in GV voicemail).
Our minutes used has gone down since all of our outgoing calls are now free (GV dialout number is in our faves list), and the other 9 slots in our favs covers our top talkers easily. This has also allowed us to drop our landline down to the bare minimum (metered local, no long-distance) and only use it for incoming calls now since we can do all outgoing through the Android GV app.
No need for an SMS option on our Verizon plan anymore (more $$ saved) since we're using GV's SMS for texts, and it's just as easy to send a pic with gmail as it is to use MMS.
Lastly, I'm about 2/3rd done with an ASE python script on the phones which will automatically enable/disable ringing to specific phones based on my location or other condition. So I can have my home phone only ring via GV when I'm actually home, or I can stop my mobile phone from ringing when I start my SIP client on the phone. And anytime you want to transfer a phonecall from mobile to landline you just hit "*" in-call, and your other lines will ring. Pickup and you're no longer using incoming minutes.
GV is awesome.