MBA is far from ideal Linux machine - Apple's EFI implementation is well known to be crappy to the point Linux kernel developer mjg59 routinely blogs about it. Power management sucks - for example - it runs hotter, battery dies in 2-3 hours tops. On my X220 I can get 6+ hours and it never gets hot.
[EDIT]: Check this out http://ubuntuforums.org/showthread.php?t=1810275 for the pain involved. In comparison my X220 had one minor issue that occurs under heavy load but can be easily fixed.