It's a launch, doesn't matter if it's only one market, what else would you call it? If their selling it to customers in the store it's not a test or a beta.
I give MetroPCS credit for getting to both LTE and VoLTE before any of the other big guys. I know MetroPCS's LTE speeds aren't what most people would call 4G, but that's a spectrum deal.
For a smaller company to be able to take on the technicail challenges of launching LTE or VoLTE before bigger competitors is a technical accomplishment and some praise is deserved.