Links?
I know I'm going to hear "this is BS", or "you can't trust those guys reviews", but here goes.
http://www.trustedreviews.com/opinions/macbook-air-vs-samsung-series-9_Page-2
http://www.itecholic.com/macbook-air-13-inch-vs-samsung-series-9-battle-of-the-thin-books/
http://reviews.cnet.com/2722-3121_7-1108.html
In some the MBA won, in some the Series 9, but I got the distinct impression reading these reviews that both machines are very capable and you can't go wrong choosing either.
IMO the 13" Series 9 and the 13" MBA look very similar, I would give the edge to the MBA in the trackpad while the Series 9 has a much nicer screen.