Seriously, when I see those products next to each other all I keep thinking is that the MBA looks like the solution of the problems that the surface has. It seems like such a fiddly device, that kickstand, the keyboard, the pen. Why do I need to keep track of three separate parts to use it to it's full extend?
I don't know what it is, but it seems like a really naive approach to the problem.
"We want a device that's a tablet and a notebook at the same time"
add a detachable keyboard
"How do we keep the keyboard from getting lost?"
add some magnets
"It doesn't stand upright"
add a kickstand
"But you can't really use Windows with your fingers"
add a pen.
It's just like the designers failed to see the whole picture and that whatever they came up with is just a bad idea. All problems that the surface solved are solved MUCH more elegantly in every notebook, except the idea that it should be a two in one device. So to me it seems like that's the problem: Microsoft was so inhibited by the idea of this two in one device that nobody else had yet, that they just were too afraid to drop the idea altogether and consequently lose the opportunity to be the market leader in some domain.
In the end and not for the first time in their history the market needs to make the decision, and I guess it's thumbs down again.