I have owned both this TV and the very similar JU6000 - Samsung UE55JU6000 55-Inch Widescreen 4K Ultra HD Smart Wi-Fi LED TV with Freeview HD
. Both in the 55" variants.
I had to return that one due to Blue blob of a cluster of dead/dodgy pixels that appeared in dark scenes/pictures. It was very noticeable - at least half a centimetre diameter (Not bought through Amazon, but during Very holiday sales with 0% interest) When it came to ordering it's replacement, I opted for this slightly newer version and the upgrades, though they seem small are a godsend;
*The stand is now located in the centre, meaning you can swivel the TV to the direction of the viewer easier. Even on a fairly large and deep TV stand, there is only so far you can go with that TV. This direction angle seems to be more important on such a large TV.
*The TV remote has been upgraded and has much better signal range and button layout.
*The TV can now output lower resolutions like in the bios of a PC. The older JU6000 would simply say "No Imput Signal" during low res, boot-up etc. and a few other strange resolutions quirks.
On both TV's though, the picture is stunning in 4K and the content is fairly easy to come by now if you have a PC especially and know where to look. But high quality 4K, of the like I'm hoping to see from BBC nature docs will looks stunning. Sometimes it is like looking through a pain of glass!
I did notice some background light source when I study the screen intentionally on both TV's but these are budget large 4K TV's so it is to be expected. Make sure you study your screen for dead pixels though as I now seem to have a tiny, almost imperceptible pink dead pixel that I am not too bothered about it this time because literally one pixel is so damn small and it only occurs in certain similar shades anyway.
Works well with Xbox One but not sure if they will be able to do 4K through an update or a refresh. I can't see why they couldn't for Netflix type apps etc.
The menu is equally fast/slow on both.
But maybe Samsung are having difficulty quality controlling all 8 million pixels from the production line in certain colours.
Overall a great entry level 4K TV for gaming, PC and movies etc.
P.S. Advice; put it in Gaming Mode on all input devices, the picture "enhancers" like adding extra frames on regular TV to get 60fps is off-putting and seems to add stutter/extra noise.