The Panasonic 65" 4K OLED is on display at Richer Sounds in Edinburgh. I spent about 12 minutes watching it today, in the company of the taller installer who delivered my Sony 16 days ago. The Panasonic looked very good with 4K material, though I couldn't in all honesty say that it looked any better than the Samsung 48JS9000 which was also in the shop, when it was also showing 4K material. I do have to say that when we played a 1080p Blu-ray (Godzilla, to be precise) on the Panasonic, it didn't look any better than 1080p material looks on any of my own 1080p televisions. I know that the Panasonic has deeper blacks than the Samsung, but the two televisons were in different parts of the shop and in isolation, the Samsung looked mighty fine. I don't doubt that if the two sets were next to each other, the Panasonic's superior blacks would be apparent, but I suppose that most owners of Samsung SUHD televisions don't have them sitting next to an OLED!
I had heard that on some 4K televisions, 1080p material upscaled can look better than 1080p material on a Full HD 1080p television, but that was not true in this case. Certainly the Panasonic TX65CZ952B, when playing 1080p material, didn't give me anything like the same "Wow" factor that bigboss's 1080p projector and screen combination gave me a year ago. Gel, you might have to buy lots of 4K Blu-ray discs in order to get your new television looking good ..... I do so hope that it doesn't disappoint you when it is playing sub-4K material.