Honestly, just that it is what I am used to. I bought the Steam controller mostly to play PC games that don't work well on a TV with a traditional controller. For that purpose, it's great. Anything beyond that will just take time to acclimate to.
The real surprise to me is the Link. I can't believe it's streaming so well without being hooked directly up. I have a home connection of 30Mbps.
My PC setup is backwards from most people. My powerful gaming PC is in the living room, and my work PC at the desk is much less capable. So, in the past, if I wanted to play a game with proper KB&M, I would stream from my living room to the desk.
So in that regard, while I wasn't using the link, I was heavily using in-home streaming and was very happy with the result. Minimal lag, felt often times like I was playing locally. I use a lan cable, too.
Nvidia's solutions are also great - I have a shield and, especially when wired with a lan cable, it's great.