I just want to report that I bought this game to play with my brother, and although we don't have a lot of free time to play it, (only played 3 games together and 2 solo so far) it has been working great and easy to set up.
We played once using our cellphones (free family calling), once on my wow guild's vent server (there's a reason I don;t have much time to play sins), and once on his spare PC.
In every case I just needed to install the game through impulse and make sure the firewall was allowing it through.