I have signed up and used the site and it is nice, but it is kind of jumpy sometimes. I can run it to my tv and watch everything big screen but it isn't quite as good of an experience as using OnDemand. The positive is that it has every episode of HBO original programming. Yeah every episode.
Next week, I plan to watch episode 7 right after episode 6. I will watch it on my 42" screen and I expect it to be jumpy and full of artifacts, but I will watch. It will probably be more jumpy as everyone and their brother will be accessing the site for the same reason.