New P759-G1 owner here. So far my impressions are mixed. Picture seems good (but this is the first TV I've bought in 7 years and I have nothing to compare it to), and the audio is way better than I expected. Don't use the built-in OS (do everything through a Roku Premiere+) so I can't comment on that. Non-4k content is noticeably bad from ~11 feet away , but I expected that, and bought the set knowing that as time goes on, more and more content will move to 4k. My biggest issues are with HDR. The biggest problem is the blacks - is it normal for the blacks in HDR to extremely gray?
After turning HDR on I thought that the overall color looked "washed out" - in particular the black looked very gray to me. I thought maybe I was crazy, but then I found a (supposedly) HDR video on YouTube that was simply a black screen. With HDR (I think they call it UHD Color which is toggled on/off on a per-HDMI port basis?) off, it was black. With it on, it was unquestionably gray - the difference between the two so huge I couldn't believe it. I don't know how to explain how huge the difference was but it was completely shocking - it was like looking at the sky at night vs. at noon during a thunderstorm. The only way the HDR black screen actually looked black was to turn the brightness down to 10% - is that to be expected?
Is this normal? And to make matters worse, when watching what I think is an HDR video (i.e. the YouTube title says 4k HDR - is there a way to know for sure that the video I'm watching is HDR?), I see absolutely no difference in the (non-black) colors if I toggle HDR on/off. Am I doing something wrong?