Tried it out last night and had a great time!
My wife and I live in an apartment with a 55-inch TV - which I normally enjoy for playing my games on but my wife is sensitive to flashing light/moving images in her peripheral vision - so gaming is often when she's out or asleep (fortunately she needs a lot of sleep!) - so this is ideal for me to be gaming while she watches some TV.
I naively went straight for Gears of War 4 mulitplayer and made the virtual screen as big as I could while still being able to keep it all in my vision - and it made me feel a little nauseous straight away. So I moved the screen away a little and found that that made a significant improvement.
I was awful at Gears (which, lol, isn't unusual) but obviously streaming from XBO to PC will introduce some lag - so there's no way I'm playing Halo 5 on this.
I then switched over to Final Fantasy XV and had an amazing time. Keeping my settings as they were from Gears 4, I actually found that I forgot that I was even in VR after a while. It was fluid with some minor streaming compression artifacts here and there. This might be due to Oculus' ASW technology too - so it might be nice (if possible) to have an option to disable that.
Given that on an XBO controller, if you press the Xbox/guide button when you're using Oculus Rift it takes you to the Oculus Home screen, I suppose I hadn't thought "How do I bring up the XBO guide then?" - and the little software button floating under the virtual screen works very well as a replacement, double taps even work for popping the mini-guide to check on Achievements etc.
I'll definitely be using this more and more in the future - tonight in fact