I've used one (briefly). The controller is "ok", although far from the most comfortable.
As for comparisons to a mid-tier Gaming PC - it really depends on the strength/stability of your internet connection.
AFAIK, they haven't implemented streaming from a central server (like the nVidia Shield)..... you're still only streaming local content from your "main" PC?
Looks like the Link is still ~$30 and doesn't include the controller?
For the money ($30 + $95 for the controller.....or $50 for simply "a.n.other" controller) $80-$125 range, I wouldn't recommend it.
I'd be much more inclined to look to an Nvidia Shield (assuming you have an Nvidia GPU in your mail rig).
https://www.amazon.com/NVIDIA-SHIELD-Streaming-Player-Controller/dp/B01N1NT9Y6/ref=sr_1_4?ie=UTF8&qid=1514915663&sr=8-4&keywords=nvidia+shield
While it's more money ($200), you get a much better (IMO) controller, substantially more functionality*, much, much more "raw" power and can stream a solid amount of titles you don't already own, by going the monthly subscription route.
*Youtube, Browsing, "Android TV" in general, Kodi, PlayStore etc.