I think everyone saying "yes I see a difference" should be doing some double blind validation. I've had people tell me they could tell the difference between 720p and 1080p at 20 feet. That is physically impossible for the human eye.
See: http://www.anandtech.com/show/7743/the-pixel-density-race-an...
My example of tv screen and resolution is geared more to this: http://carltonbale.com/1080p-does-matter/
Take an 80" 4k tv, you need to sit about 5 feet for an average human to see the difference.
I'd like to see equivalents for phones and dpi/screen size and distance.
Also 20/20 is not only not perfect vision, it's not even average [1]. So using that as the baseline is stupid, it's the low end not the high end.
Second the human eye does not have a fixed arc resolution, different specific detail scenarios have different degrees of accuracy. But if you're going to use this shortcut, you better go with a number on the upper end of things instead of the lower end, so more like .4 arcminute.
The net result is there is real, technical merit in going all the way up to 600 PPI assuming it's held 12 inches away. There's still arguably value to be had beyond that, but it starts getting more into just being a pointless spec war. Right now, though, we are very firmly well inside technical worth.
1: http://precision-vision.com/Introduction-to-Visual-Acuity-Me...
Well that would depend on the device. If it's a 5" phone, then yes, obviously. If it's a 21" display, also, yes. If it's a 75" TV, probably not.
- PPI/resolution
- Media quality/resolution
- Distance
- Panel quality/size