Quality of service on St. Thomas?

I've checked to confirm that I will have service on St. Thomas, but is there any way to judge the quality and extent of VZW coverage?  I'm concerned because going back a couple of years there are traveler statements that only AT&T and Sprint work on the island or that International rates apply.  I can see that the USVI are now covered by domestic rates - does this mean that Verizon has a partner network and the same level of coverage as other carriers?

I'd like to see a Verizon coverage map to tell if service will be available in areas that we're visiting.  I'm planning to use waze in the rental car and don't want to end up driving blind if I lose coverage.