Games look amazing, I run a xbox one through a Sony DN860 receiver (sucks it doesn't support HDR+ and HDMI 2.2!)j. The steamlink app works well as well and the T.V. does a good job of supporting controllers. I manually calibrated it a bit and to get the absolute best picture you do need to change video setting modes on different sources but for the picture quality and performance its cool.
Really the only thing that kind of sucks in my opinion is that there isn't a Twitch app and you can't cast Twitch and certain things like videos from a chrome web browser. If I really want I can just move my chromecast over to it though. I got a open box like new and it was like new. I had to buy a piece of wood to put on my TV stand to make it a tad bigger as it barely just fit on the T.V. stand and my apartment doesnt allow any nails or anything on the walls. UHD looks crazy good but not like a huge huge deal, you really need perfect or very good vision to appreciate it fully but you can definitely tell the difference. Even text like subtitles is just super sharp and easier to read. I like to watch Starcraft 2 pro games and they look amazing and you can easily read even the small text and whatnot in the U.I. or overlays. The contrast is quite quite great with very high levels of brightness. The screen with its anti-glare coating is fine and good for a living room T.V. that might be affected by sunlight and light sources/glare.
Gaming: Motion is great and one of the reasons I bought a more expensive, mid-range TV - having native 120 fps. It beats my Dell S2417DG G-Sync 144+ hz monitor really in motion and picture quality, though ULMB mode on that monitor is super fast and great at 120 hz, that mode reduces contrast and brightness. The game mode settings aren't the greatest out of the box in my opinion and it appears it has a similiar mode to like ULMB which makes ghosting almost non-existant. Input lag is not such a big deal to me on a T.V. but it has very low input lag as well.
I kind of wish i would have got the 65" model but its fine, this T.V. even on sale (after Christmas) is expensive enough for me. I'm not a huge TV person but I do watch a decent amount of stuff.
Edit: The picture adjustments I read about and made - pretty much just need to turn up the blue slightly (Blue offset and gain - just a bit like +1 +1 or so) under white balance in the advanced picture settings and yeah, colors look pretty accurate and good in my opinion.