I'm finally able to answer my own question as I just got my IPad air 2 and I'm disappointed to say that I've never seen an ipad with such terrible bookspine shadow as the one I received from apple store today.
I'm going to ask for a replacement of course as this is unacceptable, even worse than the ones I've seen with the ipad air 1.
I'd take that over the yellow tint all day long. Mine has somewhat of a spline along the top but it's not enough to warrant an exchange.