It just depends on the content. I have a 4K 65" TV that is at the upper end of mid-range in quality and 4K is definitely a noticeable improvement over 1080p in most instances, but a lot of the time it’s only noticeable if you’re specifically looking for it and doesn’t actually improve the viewing experience all that much. I do think it’s worth the upgrade though, just for the instances where it really does have a positive effect. Like, watching the Hong Kong fight scene in Pacific Rim on a good quality 4K display is just an entirely different experience than it is on a good 1080p display.