The LG UF6400 LED TV is the second 4k TV we have seen from LG which uses the less accurate RGBW pixel structure. Like most other IPS TVs, its picture quality isn't that great due to poor contrast ratio and black uniformity. Its wide viewing angle is its strong point, but unfortunately, this TV doesn't excel at anything.
Unfortunately, the LG UF6400 isn't a great TV. Movie lovers will find that the picture lacks some punch and gamers won't be satisfied with the responsiveness. Even if the TV is compatible with most PC inputs, the lag and somewhat-blurry 4k resolution will still make it a no-go. The only scenario where this TV could be viable is in an average-lit room with off-axis seating. For most people's needs, there is a better TV than this one.
This isn't the worst TV we have seen for blacks, but it is still near the bottom of the list. Blacks will look gray when you watch this TV in the dark.
This is always the strong point of IPS TVs. The colors of the UF6400 don't lose much saturation when viewed from the side. This TV is suitable for a wide family room.
Update 01/06/2017: We have changed the methodology of testing. Since this is an old TV which we don't have anymore, we extrapolated the results from 2016 TVs.
For 24p sources like Blu-ray, the TV is able to remove judder correctly. Unfortunately, movies over cable or from some streaming services will still have judder inconsistently. Since this is a 60 hz TV and it has TruMotion, it can only interpolate signals under 60 hz.
Under game mode, the TV is responsive enough for casual gaming, but any hardcore players will feel a bit of lag on their controller inputs. Compared to other 2015 TVs, the input lag is average-high.
Most of the modes tested work on this TV except for 1080p@120Hz. To achieve 4k @ 60Hz turn on 'HDMI Ultra HD Deep Color'. To add chroma 4:4:4, enable 'HDMI-PC' under the picture menu. Unfortunately, if you use the TV as a PC monitor, the input lag (same as in game mode) will be quite apparent. Even more so for games like first person shooters, which require fast reflexes.
WebOS is a great smart TV platform and has a good amount of available apps. Unfortunately, you don't get the smart remote with this TV, so it isn't the best way to experience the platform. It takes more time to input text, but other than that, the navigation is straightforward. You can read our overview of LG's WebOS here.