RingPlus does do advertising and datamining, and part of the advertising is replacing the ring notification on outbound calls with advertisements.
They have some interesting features such as their auto-translate, but they're routing through their own VoIP servers to do all this stuff, and it can impact call quality a little bit. That said, I'd still recommend RingPlus over Republic Wireless... but not by a whole lot. One positive, they do have support.
Basically, they support any Sprint handset with a clean ESN, and reception will be similar to Sprint coverage for your region, and they offer VoIP service for WiFi calling if needed. If you're already on Sprint, they're viable... but you'd be better served switching to an MVNO on the network you're already on using the phone you've already purchased. Check the guide for some solid options.