I really like it.
I use it a LOT for watching videos and YouTube. It’s great in Bigscreen’s big cinema environment. I have to make myself not use it so much for that, just so that I have a break from it! Watching a real world TV, although far superior image quality wise, is nowhere near as good as being in that virtual cinema.
Love it in Elite Dangerous and Subnautica. It’s soooooo immersive with that wide FoV. I mainly use Normal FoV, sometimes Large.
Text in game is easily readable, if somewhat fuzzy.
I have never felt ill using it, and I have had it on for many hours in the day - with bio, food and drink breaks, of course 
It wipes out the original Vive and Pimax 4K, as far as I am concerned. The Vive made me feel ill after 20 minutes of use, and I had visual issues with the 4K. And of course the FoV!!!
Image quality could be better, and I’d also like a larger sweet spot, even though the existing one is a very good size.
I think from here on in, I won’t be going for HMDs that use upscaling. 8K is good, but not quite good enough.
Due to the fact I do not feel ill using this HMD, I am quite tempted to buy this loaner, just in case the 8K X does make me feel ill. Plus, I love watching videos with it, and playing games that have been properly optimised for VR.
Oh, and I have had no issues with the headstrap. Fits well, and is very comfortable. I don’t even notice it.
Better image needed
Bigger sweet spot needed (or even better, implement foveated rendering), as @vinci says above 