The UE40JU6445 has a maximum display resolution of 4K Ultra HD. That's over four times the display resolution of the most frequently found HD type of Full HD. 4K Ultra HD TVs have a resolution of 3840 x 2160 pixels.
This TV's display resolution (4K Ultra HD) is actually the best display resolution across all televisions of this spec and age.
Across similar types of TV the worst display resolution is HD Ready.
4K Ultra HD TVs have a resolution of 3840 x 2160 pixels.
Alternative 4K Ultra HD televisions currently available which you might want to look at include the Hisense LTDN40K321 (£344.38) which has a better Rating.