The 11” Air was one of my all time favorite laptops and the 12” rMB was such a great replacement.
The form factor was just amazing, and even though the Core2Duo CPU wasn't anything special, with the SSD (at the time, they weren't very common) it was still a very usable machine. The battery life was my biggest complaint, only about 4 hours, and they didn't fix that until 2014.