I have been using Google Voice (GV) extensively for a quite a while. I use it primarily for work. I actually use it for all of my communications for and with work. They think that it is my only cell phone number. The beauty is that if I do not want to be disturbed, I set GV to "do not disturb" and it sends all of my GV calls directly to voice mail.
I have my GV voice mail set to send me an email when a message is left. That comes in very handy if I am in a meeting and can't listen to a VM. I can just check email and read the transcribed message.
My real cell phone number is only given out to family and friends. That way they can get in touch with me whenever they need to. I have an Android-based phone on which I have an app called
Voice Plus installed. I have this set to call friends and family with my real cell number and everyone else with my GV number.