Its hard to see where the iPad Air could be any better...yes more RAM, a faster processor but as it is, I think the current Air is what the iPad was really meant to be - hardware at a minimum and the internet just flows from it.
Thinner and lighter? I guess it could be but the current form factor is pretty compelling. If it was 6mm and 50 grams less I guess it would be better but as it is, its a pretty impressive package.
It's a good feature that the internet just flows from it. With my iPad 4 I need to chase the internet around. I've lost 20 lbs.