I use this a lot and I'm quite amazed at how well it works. I've only used the wired connection so I'm not sure how wireless streams but if you are streaming wired and have a decent computer you will be getting 60fps without any hit to graphics (none that I could see when I was streaming it to a 60" TV)

It would appear a lot of people complain about the steam link not working correctly, but it seems they are only using it in BIG PICTURE MODE. You do not have to use this mode, it's just the default. If you want you can click on the little icon up in the corner of the screen to exit big picture mode and you will have a carbon copy of your desktop. This is actually the better way to play games that start with a splash screen or if you are running a game for the very first time so you can deal with the firewall pop-ups. If you are using big picture mode and these pop ups appear, you will not be able to see them and the game might not start leading you to think the game froze.

Like I said the steam link is great because you are not limited to only streaming steam games. You can again, go to desktop mode and run any other game or program (such as GOG or MMO's) without having any issue. You can browse the net, watch YouTube, Netflix, pretty much anything you can do if you were sitting directly in front of your computer.

My only complaint is that there are not enough USB ports but that can be remedied by adding USB hubs and they work just fine.
I am also amazed how well the Logitech F710 Wireless controller works with the steam link. It seems purposely gimped when using it with the windows operating system but when you use it through the steam link, it works just fine. You can also use a PS3/PS4 controller (directly wired. Possibly work wireless but not tested), the Steam controller, and the Xbox controllers (wired and wireless work that I tested).
So I think this is a great product but it helps to have some level of tech knowledge to get it to work to your advantage.