there is a clear difference, try go to a website with some text.
And ignore all the fuzzy images on the retina display.
To be fair, I am pretty nearsighted, and I have that early 40's farsighted thing creeping up.
OTOH I can see the benefit of the smaller form factor and improved airflow.
We are talking about retina display, not the lack of support from images that websites upload.
With text, its easy to spot the difference.