I bought one of the 55-inch models from Best Buy during their "Beat Amazon to the Punch" sale.
I initially had to take it back for an exchange because the first one I picked up on Tuesday had a large dark spot in the lower left corner - looked like the backlight wasn't illuminating in that area causing about a 5-inch-long "shadow" that was super distracting. I returned it to a store that had more in stock and exchanged it for another one without issues. The folks at Best Buy said they had some heard of a few being returned for similar issues but hadn't seen the problem themselves, despite selling many of them over the past couple months. (The manager said that most of the returns were for size issues, not defects.)
So far I'm loving the TV. It's quite an upgrade from my 10-year-old, rapidly dying JVC 32-inch 720p set. The little 4K content I can access on YouTube and Netflix looks great. I do notice a bit of moire on really tight patterns, which causes a small amount of flickering, but not enough to be distracting.
But I do have a question about the HDR implementation. I can't find any option to turn HDR on or off anywhere in the menus. There's an option called "HDMI UHD Color" and "HDMI Black Level," but they're only for the HDMI inputs, not for the TV itself, including apps. So is the TV auto-detecting HDR content and applying HDR settings? How do I check to see if it's working? I played a bit of "Marco Polo" on Netflix, which is HDR, but I can't tell if the dynamic range is any different than normal. HDR isn't even mentioned in the TV's manual. So, where is it? Any ideas?