I've been reading reviews, tons of reviews, all so that you won't have to. In case you want to see what the people with review units have to say about the device, follow this link from iMore:
Read one, or read them all. You will get a consistent message. The iPad Air is an incredible feat of engineering that really has to be held and used to be fully appreciated. It is the best tablet computer on the market, and redefines the state of the art. Though the marketplace is very competitive, the real competition is between the iPad, and the other iPad. Either way, you win.
I intend to post my review this weekend. Stay tuned...