The retina screen is definitely better, but the Air can be upgraded to 8GB of RAM. The overall design of the new MacBook is revolutionary, but I can't believe they chose a CPU that is considerably less powerful and charge a premium price. If you can stand 1.5 lbs more, you can have a MacBook Pro for the same price which is considerably more powerful (also with a retina display).
I disagree. As someone who used an Air and then MacBook Pro Retina 13", the weight difference is small but definitely noticeable for the worse. If you walk a lot it makes a difference.