So my 23-inch ACD has 1920 x 1200 pixels for approximately 9,645 pixels per square inch.
My HTC Sensation 4G has 540 x 960 pixels on a much smaller display. The pixel density is 65,828 pixels per square inch.
Do I see pixelation on my ACD? No.
Do I sit up close with a magnifier? No.
Any further improvement in pixel density would not be a reason for me to buy a device with a so-called retina display.
That's great, keep your ACD. You have to understand a lot of people *can* see the difference between, say, a typical computer display and printed text. For those of us, quadrupling the number of pixels is *extremely* welcome. I can easily see the pixels on the 23" ACD in front of me as I type this. It doesn't bother me, as I'm used to it. But to have everything much smoother will be a welcome enhancement IMO.