It's not really much different from 17".
I don't know, I've played with Sony's AW in a store, and...it simultaneously seems huge, and kinda small. I mean it's really small considering how big the screen is...I don't know. It's actually the same width and slightly longer than my current keyboard (and narrower actually than another keyboard I have at my desk)...so...I don't know.
I'm kind of scared of it's size, and yet kind of not.
It's I think like 8.6lbs, which interestingly is only a few inches more than a Dell I was just helping someone with from 2003...that was a 15" system! It's several POUNDS lighter than some 17" systems...so again, it's kind of huge, and kind of small...at the same time, i don't know.
Hopefully its cooling system seems more robust than Apple's :-/