I have two GV numbers. One is used with our Obi-200 VoIP adapter for totally free landline service. The other is used with Hangouts on my mobile phone for all texting, voice calls, and video calls. My phone has an actual phone number from Ting, but I don't even know what it is. The only number I provide to people is my GV number. And I have all conventional text/voice functionality disabled using the Ting device setup.
This has a number of advantages: (1) no spam calls or texts, (2) I don't pay Ting for voice or text usage, (3) I only pay Ting for mobile data usage when not in a WiFi area (rare), (4) when I'm overseas, I can call the US for free in a WiFi area, and (5) voicemail transcript sent as text or email, so I know immediately if I missed a call on the home phone.
A couple disadvantages: (1) voice quality can be sketchy if I'm not in a WiFi or 4G area (increasingly rare), (2) Most verification systems work fine with GV, but as gauss mentioned, some don't recognize GV as a legitimate mobile number. They think it's a VoIP number. I had trouble signing up with Uber for this reason. Uber eventually accepted the GV number but only after I opened a trouble ticket and some back and forth email with their tech support. There have been a few other instances like this but there is almost always an alternative means of verification like email.