I only heard of this service because of their promotion last week. I knew about Freedompop before, but this fits my needs much better.
PSA: RingPlus service is perfect for certain types of people with kids who don't really need phones except in the case of emergency. The biggest advantage of it over Freedompop IMHO is that you can connect dumbphones. I want my kids to have an emergency phone when they go places by themselves, but it's not worth paying for a monthly plan for them and I'm opposed to giving them a smartphone.
I bought a 3 pack of Dura flip phones on ebay for $15 and connected to the free plan.