I'm still rocking my MBA form 2010, it wasn't even top spec at the time, but the keyboard, size, weight and battery are all great. The screen is pretty terrible I'll be honest, but if I'm working on it it doesn't bother me much. Plus it has one of those ever so rare HDMI out ports (no accessories necessary). I just replace the battery every so often.

I'm currently weighing up the option of installing Linux onto it as I'm more inclined to move away from the Apple ecosystem, but I have reservations on what that will do the battery life :/