I was up for a new computer when the macbook just was coming out so faced the decision of macbook or 11 inch air and went for the air. I think for my use I will ultimately be a macbook user since I think portability is my top concern, but the 11 inch air vs the macbook right now I think the air is a better product.
The processor is very competitive in the air line unlike the macbooks and you get all the ports you would need without needing any adapters. plus if you compare the 11 inch to the 12 inch macbook the weight as size are pretty comparable.