I've been exclusively using Google Voice for months now, and just for voice mail for more than a year. I feel like the plain-old telephone system (POTS) is an unreasonably high toll to pay given how technology has improved. There is no reason to have non-trivial long-distance rates between Europe and the U.S. in a day when Skype does it for around a penny a minute. Google is doing a wonderful thing by promoting an Internet-based phone number.
Rather, Google is starting a wonderful thing. In the time I have used it, many of the most obvious problems haven't improved in the slightest.
Here's a quick run down of the good and the bad as I see it. Overall, I see it as comparable to my two-year stint using a Mac for software development. The promise is there, but when you actually try it, you realize why it's not yet the norm.
I love receiving calls and having all my devices ring. In 2013, it's the way things ought to work. If I'm in the car, my car stereo should ring. If I'm at my desk, I should get a notification on my desktop. If I'm watching TV, my physical phone should ring. Google Voice gets this just right.
I love the option to take calls at my desk. I already do a lot of voice chat sessions with coworkers around the world, and it just seems right that I should do the same thing with gmail addresses and numeric phone numbers.
I love the text transcription of voice mails, for those times I can't take a call immediately. The quality is iffy but is usually high enough that I can understand the gist of what the person was telling me.
Phone number porting works just fine, so you can keep your pre-existing number and not even tell people you are using Google Voice. Well, you have to tell them for a different reason: there is so much bad with Google Voice that you need to warn your potential calling partners about how gimped your phone service is.
The BadThere's a lot of bad.
It doesn't work over data connections. I really don't understand why it is missing. Because of this problem, I have to buy minutes on the POTS to use it on my cell phone, and minutes are far more expensive than the associated data cost. More pragmatically, if I am travelling and don't yet have a local SIM card, it means I cannot use my phone to call over a wifi network.
You can't make or take calls directly from the Voice web page. You have to log into both Google Talk and Google Voice, configure Voice to talk to Talk, and then make your call from Voice. Yes, you can also make a call from Talk directly, but that's a separate feature of the Google suite, thus confusing matters even further. Google is normally excellent at building web user interfaces, but that seems to go down the tubes when an issue crosses multiple teams.
When you make a call at your desk, using Talk, the volume is extremely low. I originally thought that was just my configuration, but some web searching indicates that this has been a widespread problem for several years. I have to turn up my system volume to the max just to barely hear the other person, at which point every random system notification is an ear splitter.
It doesn't support phone usage from the UK. This is a very surprising restriction, because Talk can make calls to the UK just fine. Part of the benefit of Voice for me is the promise that I can travel around and call POTS numbers from wherever I am. However, even if I get a UK SIM card, it's just not supported by Voice.
There is no MMS, and there is no warning on either side when an attempted MMS does not go through. I have to tell people to use email, or to use my physical cell phone number rather than my Google Voice number. If Mom emails me a photo of one of my nieces, it quietly disappears. I am oblivious, and she is wondering what planet I am on that I didn't write back.
The ugly part is that Google is not doing anything to fix all of this. I'm willing to be a beta tester in this case. It's not beta testing, though, if they never fix the problems.
At this point, the POTS tax is substantially higher than the Microsoft tax of yore. It costs tens of dollars a month to participate, and you can't live without it.