The Air is light, thin, snappy. The keyboard is fine. I'm having a little trouble getting used to how thin it is, how the keyboard is literally hugging the desk. But that will pass.
The solid state disk, curiously, is not quite the game-changer I expected. Battery life is fine, but it's in line with other Mac laptops of recent vintage. (The lack of the swappable battery doesn't annoy me, as I'd pretty much stopped swapping the battery of the 12" AlBook, even on long flights. Which hasn't kept me from lugging it across many continents and several high hills.)
It's an impressive little machine. Not well suited to being your main workhorse, but ideal for a second workspace. That's going to place more stress on backup (hello, Time Machine) and synchronization (someone needs to find a UI that explains sync failures to users and provides sensible corrective actions; the current crop of tools are just not doing it).
The big lesson was that our office wifi network is buggy. Switching to our backup network — we rented a second network connection from the law firm down the hall after the great Verizon flap — made the Air's file transfer much nicer. Again: there should be better ways to diagnose a fouled up wifi network. PING tells me "this is not right", but (a) that's too technical for most people, (b) even a fairly technical guy like myself might not really know what PING should be reporting, and not everyone has two wifi networks on hand to compare, and (c) I definitely dont know how to move from "this is not working well" to "you need to replace/reconfigure/get rid of this base station/relay/cable/ISP."