I decided to do a quick screen comparison between my new iPad and my older iPad 2, using the Olloclip macro lens on my iPhone 4S. I think this test shows the difference in pixel size pretty dramatically.
I used the following iPhone picture of Texas bluebonnets as my test image – specifically I used the little white molar-shaped part of one of the blossoms just to the right of center:
Here is that blossom part on the iPad2 screen:
Here is the same blossom part on the new iPad screen: