If you are deciding between these two new machines, highly recommend you walk into an Apple store and literally hold each laptop in your hand — you’ll be amazed that there is nearly no difference in weight, and the MacBook Pro is actually narrower.
And I was a bit of a skeptic on the whole Retina thing, but the high resolution display does in fact makes a huge difference, to the point of making non Retina screens pretty tough to look at. Battery life has a slight edge on the Air, but still solid overall (12 hours for Air VS 9 hours for the MacBook Pro 13″).
Mashable literally just weighed-in with the same conclusion:
The 13-inch rMBP weighs just 3.46 pounds.
While that weight is north of many Ultrabooks, it’s still plenty light (which I acknowledge is an oxymoron). I had no issues with taking it to meetings, throwing it in my bag to take home every night, and flipping it open for some comfy computing on the couch when I got there. The 13-inch MacBook Air, at 2.96 pounds, may be lighter, but its overall footprint is actually larger than the 13-inch Pro’s by about a centimeter in width. The Pro’s thickness is just 0.71 inch, almost the same as the Air at its thickest point (0.69 inch).