I was given one to use from my school. I haven't been a Mac guy since i "upgraded" from a Macintosh Classic circa 1996.
Holy crap the thing is small.
Holy crap the thing is fast! It's all flash drive, so the thing boots up in seconds.
I'm still learning on it. Of course, the interaction between the Air and the iPad is seamless. We're going 1:1 iPads next year, and I'm putting together "textbooks" on iBook Author for my classes.
Everything saves to iCloud, so it's transferrable to all my computers, even PCs, I think.
The question is, of course, is the Mac worth the money? It's a question for the ages, I guess.
