Would be nice if they had some data about how well their service works. Would also be nice to see what hardware requirements there are, battery life tradeoffs, etc.
Rosum's TV Advantage
In contrast, television signals were designed for indoor reception. Rosum TV-GPS uses commercial broadcast TV signals to provide reliable positioning indoors and in urban environments. By combining TV signals with GPS signals, Rosum can provide seamless indoor/outdoor coverage across all environments.