Enjoyment of Video games, cost of consoles, and accessories, and cost of video games are factors which are important to me when buying a console.
Steambox looke pretty good since it already has access to a lot of Steam games which are out, and you can install non-steam games from Linux games stores like the Ubuntu Software center, and Humble Indie Bundle for Linux, so gamers would not need to hope that better games will come out in the future for Steambox console. I also read that Steambox is also a PC, so if the Steambox never catches on, you can still use it as a Linux PC to play PC games, do PC tasks like web browsing, and Office work, or install Windows, and use it as a Windows Gaming PC.
I agree with Nuke, buying a gaming console for media is not worth it when you can get an Apple TV, Google TV Settop Box, Chromecast, Roku,etc for $99 or less vs a console which cost $400-500.
A Smartphone and Tablet can also be used for Media since many smartphones, and tablets now let you connect it to a TV with a HDMI cable.
If you need a Blu-Ray player, you can get one for around $50, and a lot of the newer Blu-Ray players have Apps for Netflix, CinemaNow, YouTube, Vudu and Pandora streaming via wi-fi, and wired internet.