I just spent an hour typing on my friend's MBA. I found the MBA keyboard really annoying to use, it had that click that makes the whole computer feel fragile. Also, I realized that I'm not very precise on landing my fingers when I type fast; on the MBA my fingers would often hit the empty space between the keys. For example, in typing "reason" on my Macbook Pro, I essentially press down R-E-A simultaneously and just gently slide my hand towards the left, and voila "rea" gets typed in an instant. Think of it as similar to legato on the piano. But I have trouble doing that on the MBA keyboard. I don't actually press down and lift each finger.