I've been working on a formal review on it (to be published later). That said, it is beta. It works, but I do get some rather weird frame delay and audio dropouts between my PC and my Macbook. It's very possible the Mac version of Steam doesn't fully support it yet, too.
If it DOES work well, it'll be simply awesome - especially with a system running SteamOS as the target machine. Pretty exciting stuff, really.