My point may have been too subtle. The GP made the claim that it is false that the ASUS tablet is bigger. I used the same logic to show that an 8 foot ladder can be "bigger" than a 12 foot ladder. By reductio ad absurdum, the claim that bigger only applies to area is shown to be false as you'd be hard pressed to find someone who says "No, no... the 8 foot ladder is bigger than the 12 foot one". This is a concept of "bigger" which can be applied to tablets as well. Whether measured diagonally or by height while standing in portrait mode, the ASUS tablet is bigger in that particular dimension than the iPad.

I'm sure that their marketing department steered well clear of the word "larger" because larger implies an overall size advantage whereas "bigger" can be construed as greater in one dimension.