Got my free Roku 3 yesterday. Unlike on the Android app, the Spectrum TV app on the Roku does allow me to watch all the locals. The HBO live channels are not in HD though. I switch between watching the same movie on HBO Go (on Roku) and Spectrum TV HBO (on Roku) and the Spectrum one is like 480p or maybe worst. The ones on HBO Go are in HD.
The other thing is that I found out History channel app does not support Charter Spectrum TV. It listed like 50 providers but Charter is not among them.
I was kinda excited about this until you posted re. the non-HD thing. I won't watch anything that's not HD. JMHO