I'm curious to see if, at least for us Apple users, if the upcoming OSX redux (Mountain Lion) & it's ability to mirror anything on your Mac's monitor to an Apple TV box will finally allow full on AIrPlay compatibility w/ HBO Go. As it stands now, HBO Go via iOS device will only AirPlay the audio, not video, to ATV 2 or 3.
Being a Comcast customer, I can obviously get a decent amount of HBO programming OnDemand. However, HBO Go does open one up to having most everything HBO has ever aired available at the touch of a button/click of a mouse. Not having to watch it on a computer monitor or iPad screen would be nice.
As well, I would not be too surprised if some sort of subscription plan were to come about one day to allow non-cable/sat folks to pay for & access HBO. The cable/satco folks may not like it, but HBO might be better served by such a model, esp when one considers the reportedly massive amount of online piracy that occurs with HBO programming (thought I read that Game of Thrones is one of the web's most pirated TV shows).