Linux is a decent alternative because it works, and because it allows "computing" in this glorious age of the media comsumption devices. It has a %&$#?@!%&$#?@!%&$#?@!%&$#?@!load of shortcomings, but so have most operating systems on the market today.
That being said, SteamOS seems more like a gaming-inclined Linux distro bundled with a marketplace.
If it works for Apple anf Google, right?
