Dave, there is a free app, which does little. There is a $4.95 app, which runs a few locos. Some day, when the winter is over, some day, in the blush of the spring (as the song goes), there will be a $25 app that also controls switches and accessories.
I also bought my WIU from CT Trains (Jeff) in Zelionople. My first transaction with them, and I was pleased with the service.