From some quick calculations Samsung's display would be 260 dpi, which is a bit short from 287 dpi found by neuroscientist Bryan Jones to be "true" retina quality, and a lot less than the 326 dpi of the iPhone 4's retina display.
This is even before looking at the PenTile issue, which only makes it worse.
This is even before looking at the PenTile issue, which only makes it worse.