I just picked this up last Sunday. I got a hook up from a long time breh I knew who works at the nearest PC Richards. Got it for $558 after tax, it normally retails for $648 so it was a steal at that price. I mainly wanted it for my bedroom and it was the best size/price as everything else was way too big and costly.
Pros:
Set up was nice and quick. Ran Google setup and was up and running within minutes. I then did a system update, turned on enhanced HDMI for HDR content and hooked up my devices.
Image Quality is beautiful. I know people always say you gotta have X size TV to see 4K benefits but that's also dependent upon how far you're sitting. Where it's sitting, it's about 3~4 ft away from me at eye level. My PC input looks crispy as hell in 4K. The increased resolution allows me to have multiple windows open and still see the whole window/task of whatever I'm doing so the increased detail/screen estate is helpful.
Gaming wise I haven't played too many games on PC yet since my GPU only supports 4K/60hz via display port so right now I'm stuck at 4K/30hz until I pick up an adapter. I only briefly launched Forza Horizon 3 and ROTR and they looked fine.
Colors look very nice on here and I set them to the settings off of RTINGS.com. Initially I set it up correctly but made a mistake of setting the brightness up pretty high which on this TV is also tied to the backlight and typically people like to have their TV's on MAX brightness, very high colors and all these image enhancement things to make stuff "pop" but that's not how the image is intended.
Things would be over saturated, blacks crushed, and detail in bright/dark scenes lost. That made my impression of HDR in some titles seem worse as each game implements HDR differently so UC4 looked like nothing changed, FFXV looked the same and Ratchet looked washed out.
I then lowered the brightness, adjusted the contrast and made sure everything was set and also followed some tips from other users of this set from forums like AVSforums/Gaf from folks who actually tuned their TV professionally. That made a big difference. Ratchet in HDR looks beautiful as details that were crushed/over saturated looked much more normal. The average person would deem it "washed out" or w/e but you gotta get used to it. I prefer accuracy>>>>artificial image enhancement/toxic bright colors. So if you have this set or something similar, set your brightness down to minimum and play in a dark or dimly lit room. A bright room or so needs higher brightness but you lose black levels detail and whatnot.
My TV has a rating of ~375 or so nits, which technically isn't meeting HDR10 standards for brightness but that doesn't mean anything since most HDR content usually peaks out way below that and SDR content caps out at 100nits so it's still a sizeable difference. All in all i'm satisifed with the way it looks now and I don't think I'll touch the image settings until i decide to get one of those calibration testing devices and tune the advance color options manually. Those "VIVID" or picture modes on these TVs are so fake looking. Oh and make sure the PS4 or Xbox is set to Auto for RGB settings and the TV too. Mismatched RGB settings can cause the screen to be washed out or crushed which means you're pouring jelly on yourself.
The apps are pretty cool, standard google play store stuff so you can load up some stuff on here from Android.
The menu speed is okay. Not very fast but it's acceptable.
All in all I really like the TV and am only now starting to enjoy it when at first I felt something was off. I gotta play more with the games to really see the changes in HDR as HDR is not just "brighter colors". HDR and WCG means there is a wider range of colors available that the TV can now display especially at brighter scenes so it's scene dependent.
All in all I think the TV is great and I can't wait to see better/more HDR content over time.
Edit: I forgot to mention the Motionflow thing on this TV is pretty nice. usually this brings heavy input lag but in fact It felt the same so I suspect it's very minimal. It makes motion looks mother, almost like a fake 60fps but I usually turn it off but it looks great on this TV for some games.
Cons: the brightness ain't all that so it's not the BEST HDR capable screen.