I purchased this TV one week ago and I have to say that I am pretty impressed overall with the quality of the picture. This is my first 4K television, and have streamed some 4K content off the built in You Tube app. It is truly stunning. Bright, beautiful colors, incredible details. No hiccups in the stream (I have a 60bps Internet WiFi connection). The upscaling from lower video sources seems to do a great job for picture quality from all sources, cable, streaming and DVD.
HERE IS SOME IMPORTANT INFORMATION. I almost returned this TV yesterday.
After going through the settings menus on the TV to play with modes, brightness, contrast etc., I thought I had a reasonable setup. Popped in the DVD "Allied". Started to notice weird rendering on peoples' faces, both in medium and close up shots,. Then noticed ghosting as people moved through dark or very bright areas, especially evident in dimly lit scenes. The ghosting (for those unfamiliar with the term, is a light trail left behind moving objects) became so bad I was sure I had a defective TV. I tried switching HDMI connection ports, picture modes to no avail. So I decided I would have to return the set back to Walmart.
Being that repackaging a large TV is no small task, I thought I had better research to make sure there wasn't something I had done during setup to create this lack of motion handling from the TV. My Google search revealed that there many complaints about ghosting in 4K sets, across all brands. Reading one blog response, someone stated that on his Samsung TV he turned off the digital noise reduction feature in the settings menu and his ghosting problem disappeared. Lo and behold! After going into the Advanced Picture Setting menu and turning off the Digital Noise Reduction from high to off, no more ghosting!
The TV is staying. It is now a beautiful, trouble-free picture.
Since I had changed a good number of settings, I don't know if the TV shipped with Digital Noise Reduction on so maybe if I hadn't played with the settings, I never would have experienced this issue. Note: Each Picture Mode in the settings (Vivid, Standard, Energy Saving, Theater, Gaming, Sports) can be individually customized and applied, so the Digitial Noise Reduction has to be disabled in each mode. Once done, you don't have to reset it again. Since the ghosting was only happening in non-4K sources, maybe the noise reduction feature is useful when viewing 4K content, I don't know.
But this does make wonder how many people have returned TV sets because of this issue without knowing this simple fix! This TV is a great bargain at $428. I hope this set lasts the 10 years that my old 720p LG LCD did (actually still operating).