TOOK A SHORT WALK WITH THE INTENTION OF making a few intimate landscape pictures for comparison purposes. Each scene pictured with both a Olympus µ4/3 camera and the iPhone.
The results are pretty much what I suspected they would be. That is, the iPhone-made pictures compare very favorably with the µ4/3-made pictures. Both would print well at 24x24" with little visible difference unless, of course, one were to indulge in pixel peeping. However, were I to see someone pixel peeping, I would knee-cap them with my basball bat and then drag them back to the proper viewing distance so they could see the print as it should be viewed before they went to the ER.
FYI, I was not attempting to process these pictures to achieve an exact match, contrast / shadow•highlight detail / color / density wise. For my comparison purposes, close enough was good enough. I was looking for enlarge-abilty.