My new Steam Link showed up yesterday. Interesting, tiny device that comes in a much larger box. The reason for that is because it comes with numerous different power adapters. One box will be able to ship to many countries.
Pretty straightforward to set up. You hook it up to your TV and your home network, then it scans for a PC with Steam running, then gives you a 4-digit code to enter into the Steam client, then they're hooked together. And that's when you get an inkling of what this thing is: a glorified VNC session. :-) Once the Link was connected to my Windows 7 box, I saw my entire Windows desktop on my TV.
The recommended way to run Steam is in "Big Picture" mode, which makes things a lot friendlier for the living room interface. Everything is fully navigable using the Logitech XB360-like wireless controller that I sometimes use for PC gaming. And Big Picture indicates which games are controller-compatible.
When I first read about the Steam Link, I saw that it supported 100 Mbit ethernet (not gigabit) along with 802.11ac MIMO... and that the wired ethernet was recommended. This struck me as odd since the ac wireless option has vastly more (potential) bandwidth than 100 Mbit ethernet. But then I realized this was all about latency. On my own home network, wired devices ping each other in well under a millisecond while wireless devices can take 1-2ms at best and occasionally see spikes of up to a quarter second.
Naturally, those become a concern when operating this device via wireless. I played Ultra Street Fighter IV, the twitchiest action game I own on Steam, and it worked tolerably well. It ran at full 1080p and benchmarked at 60 fps. Every now and then, there would be "jump cuts" in the action, likely owing to spikes in wireless latency.
Now I'm brainstorming ways/routes to run an ethernet cable from where my Win7 box lives down to my main TV area.