The main issue I have with Freedompop is that their calling service is actually VoIP over cell network data. So, you don't have any "actual" cell calling service.
In my own experimentation, calling with VoIP over data doesn't seem to be as reliable when you're on the go (ie. making a call while you're driving) and generally uses more resources on your phone since the calling is handled by an app or equivalent (probably not an issue if you have a higher-end phone) - this can drop calls more easily, weird call quality issues, etc, if you don't have enough resources.
This is one of the reasons why I went with Tello after Ringplus was shut down. It's not that I need phone service all of the time, but for those times when I do, I can pay as I go for phone calls and have them more reliably. Yeah, yeah, I know not free but still pretty affordable.
Truth be told, I'm glad that Freedompop works well for you. Keep us updated with how it works out for you.
Also, an alternative I've been using instead of Google Hangouts is TextNow which is similar and also provides a free phone number.