I dunno, when I'm around 9 feet away from my 46" flatscreen, I can DEFINITELY tell the difference between watching a DVD and Bluray.
The 1080p TV does a good job of presenting the DVD, but it's just missing the crispness of the bluray. I remember there is particular detail when watching Blu-rays that show scenic views of a cityscape or other sweeping vista where it's more like looking through a window into the movie, unlike a DVD where it's more like a fuzzy image. I guess it's more impact when you sit closer up? I'm willing to pay more for 1080p blu-ray content, but only for movies where it makes sense. If the movie is a comedy and you just stare at close-ups of people talking to each other, then the Blu-ray is still nice but I don't mind DVD for that.
Yeah, it's easy to tell the difference between 480p and 1080p.
720p and 1080p, not so much.
A great test is to play a 720p video, and have somebody walk into the room... and ask them if it's 1080p video. They honestly won't be able to tall.
Maybe at a 100" screen, viewed 5 feet away, you can tell the difference between 1080p and 4k, but only when there is severe diagonals and contrast involved, and the TV doesn't do any interpolation.
...and the charts showing supposed visual differences at various distances and screen sizes are mostly bullcrap. They might matter in a heavily detailed, high contrast, STILL image, but not with motion, and properly aliased images.
The jump from 480p is obvious, but beyond 720p, not so much when it comes to video. A vast majority of movies are not
Samsara, where 1080p stands out because of the rich, detailed shots, mostly fixed or slow moving (and where you are not engaged with a story, fixated on the characters or action).
As a computer monitor, these 4K displays would be great... but I wouldn't play games on them at 4k. Of course, there would be benefits from the TV's interpolated anti-aliasing when playing a game at 1080p resolution, any way. My main desire would be for the screen real estate on the desktop. I already use 2 1080p monitors for development, but it's the vertical resolution that I could really use here.