rMBP vs MacBook Air?

Until today, I was considering purchasing an Air (13", 256GB, 8GB RAM) for $1399. Looking at the new rMBP 13", 256, 8GB for only $100 more, what are the advantages of one over the other? They have it down to only half a pound difference and .03" in height. Add in the higher res display and better processor, I'm not seeing a hugely compelling argument for the Air. Please let me know what I am overlooking. Thanks!