So yeah. Hooked it up and it's hard to explain how overwhelmingly happy I am with it. I already had pretty high expectations, and most of all I only have an original PS4 to hook it up to. But even then I just can't believe how good this thing looks. Even normal 1080p games, which I was worried would look like a jaggy mess on such a big TV, look impeccable. Horizon looks great, the brightness and contrast is fantastic, although not a huge difference, but I didn't expect a lot from it on the original PS4. I think HDR really shines and pops when coupled with super sharp 4K material.
What's more shocking is that normal non-HDR games look frigging brilliant! My partner is raiding on bloody Destiny (I'm so over that stupid game) and the thing looks ridiculously good. Not a jaggy in sight. No lag. Even at 10 out of 50 backlight setting, it's scorching bright. Imagine HDR material that automatically cranks up brightness to max! There's literally no reason for us to get a Pro if games look this good on the original PS4 on this TV.
What really shines is 4K/HDR material from Netflix/Amazon (my only source so far). Even my partner, who is a Destiny freak and really couldn't care less of IQ (he's been happily playing from his PS4 to the MacBook through remote play for months and he said it looked "great"...) was shocked. "Wow It looks like a real picture".
For the price, I'd better be impressed. But even then this thing went way over my expectations.