I did this but was expecting more from Google. As an example, it was easier to add two factor auth to my Blizzard account (and install their authenticator) than it was for Google. These are the steps for Google: - Add mobile phone to account - Enter code from SMS - Generate random passwords for multiple apps which don't support two factor auth (this took awhile). - I wasn't given any instructions on how to switch from SMS to Google Authenticator app so I had to search for those instructions and then set that up.

Granted Blizzard controls the entire experience, they're not dealing with 3rd party apps, but it seems like Google could make this easier. And once it's trivially easy to setup, then it can be made the default.