rMBP versus MPA 11"
I made it to an Apple Store this weekend for the first time since before the iPad 3 was release, with a mission to compare the new retina wares with my own eyes.
First stop was comparing my MBA 11" with the rMBP 15" on multiple web pages, PDFs, and MS Word documents, scrutinizing text in particular for better legibility. I was astounded that there was very little difference to be seen (and the text actually looked better in MS Word on the MBA). I brought over an Apple Store rep to compare each page with me; he was very surprised but agreed with me completely that we could find no significant difference in text readability between these two laptops. Granted the rMBP (and all MBPs) have a better-quality LCD panel and better color gamut than MBAs, but bear in mind that the MBA 11" has the highest resolution among all non-retina Macs and is arguably nearly "retina" already at typical viewing distances.
Feeling somewhat jaundiced about retina claims, I picked up an iPad 3 for the first time to compare Maps app results with my iPad 2, and this time the night-and-day difference in place name legibility started me. The iPad 2 Maps names were often very hard to make out, incompletely bordered, and blurring in with the satellite terrain beneath the letters. By contrast, all the iPad 3 place names were easy to read in Maps. While browsing, a favorite text-only web page was much more legible on the iPad 3. The difference wasn't quite so pronounced in iBooks, but still could be seen. In general, the iPad 3 was much brighter and sharper. I was very impressed by the retina difference among iPads, but could find little text quality difference between the rMBP and MBA 11".