Please be advised I only paid $299 for this TV. For this price, the TV is an absolute steal. If you pay $397+ for it, I'd still consider it a good price.
This is a really good TV. This is my first 4K TV and probably my last until 4K OLED becomes more affordable. Picture is great, color gamut, contrast, sharpness all good. Sound is surprisingly full for a flat TV, there's some decent low-end. Some people will say buying a < 50" 4K TV isn't worth it because you can't discern the difference between 4K and 1080.. well, I sit within 9' viewing distance of the TV and I have 24 year old eyes, I see a great difference between 4K and 1080. UHD content on Netflix and YouTube looks marvelous, and I haven't had the chance to see UHD+HDR blu-rays yet.
WebOS 3.0 is surprisingly good. I was thinking the first thing I'd get for this is the new Chromecast Ultra with 4K and HDR capability, but after using WebOS 3 built into the TV, I don't think I'll need the chromecast, and I LOVE chromecast. WebOS has Netflix, Hulu, Amazon Prime, YouTube, Vudu, Plex, Spotify, Pandora, Google Play Movies and TV, and I can cast most if not all of those from my phone or computer. This TV even has Miracast / Intel WiDi.
Now here's some info you might be looking for before buying this tv. YES it will "display" HDR content, when you play an HDR movie on Netflix for example, a little blip shows up in the top right of the screen saying HDR, and you get to choose between HDR Vivid/HDR Bright/HDR Standard presets. Is this TV HDR10? I'm not quite sure. Some say yes, others say no because this isn't a 10-bit panel. I will update this when I can find out more. I'm really looking forward to watching The Grand Tour on Amazon Prime in 4K+HDR. :) Oh and planet earth 2.
Gaming performance - I wouldn't buy this if gaming is your primary reason for having a TV. The input lag isn't horrible, but you're not gonna be a snap shot in CoD or TitanFall 2 with this TV, and that's with Game Mode on. I know some people can't feel a difference but I have trouble wanting to play games on this because of the input lag.
If anyone has any questions, let me know.
edit on 11/21/2016: I see some other stores are having sales on this TV around black friday at the same price I got it at, $299. I say definitely go for it if you see it at that price!! Oh and take the other "reviews" of this item on amazon with a grain of salt. Both of the 1-star reviews are not representative of the product whatsoever.