Interesting. Game controllers are a fascinating user experience design challenge. While Playstation and Xbox controllers are fairly well-polished functional workhorses, I appreciate companies (like Nintendo and, now, Valve) pushing the envelope.
More than even the games (which, I suspect, will also mostly be available on other consoles or PCs), this intrigues me enough to want to get a Steam Machine. (Still, though -- that's a bit of a cumbersome name.)
Even if it doesn't work, we can expect something to spawn from that in the future. Joypads tend to evolve across companies and products. Remember D-Pad and start-select from NES and L+R and 4 group buttons from SNES, then N64 with analogue stick and rumble while PS1 had handles and Saturn added analogue L-R, Dreamcast take it from there, Xbox took what Dreamcast had and perfected it over two iterations, while Sony... ah you get it.
More than even the games (which, I suspect, will also mostly be available on other consoles or PCs), this intrigues me enough to want to get a Steam Machine. (Still, though -- that's a bit of a cumbersome name.)