I actually like the MBA's trackpad. The rough silver feels good on my fingers when I'm doing two-fingered scrolling. Also, call me old fashioned, but I like having a button to press for things (even though I have tap to click enabled). I preferentially use the button for dragging items around for some reason. Because the button doesn't register my thumb's presence on it, I am actually faster using it. I leave my thumb there and use multiple fingers all over the trackpad to get stuff done clicking and non-clicking whenever appropriate. On the glass trackpad, I can't rest my thumb there, it just freezes the trackpad.
I agree, the trackpad on the air is the best...hands down, not sure why but it is on both rev. A and now rev. C, still better than all others including uMBP 13, 15" and 17" and of course the older pre-unibody MBP...