Is Apple's iPhone Retina Display really accurate to human eye resolution?
Until peer-reviewed data on the topic is published, all we have to go on is blog posts from vision and display researchers. The best posts I've seen so far are:


  
  Artal, P. (2012) Is the display resolution of the new iPad adequate for the eye?
  Artal, P. (2012) What have in common the Apple “Retina” display and our retina? Probably, only the name.
  Soneira, R.M. (2012) New iPad Display Technology Shoot-Out
  


To summarize: Some people can see the difference in some cases.