It's more than a carbon copy of the dex. It's made using Apple's authoring software (free) to get all the fancy interactivity features. The output of this app is exclusively sold in Apple's book store. There is nothing stopping GW from taking their original copyrighted material and transform it in some other way and sell it.
This digital dex is nothing short of sci fi. For those of you that are young let me remind you that this would have been impossible ten years ago (and I was working with the top of the line prototype smartphones of that era). This is mindblowing type of stuff. This is what Star Trek almost had in their shows.
I personally is happy that GW went with a high quality product (I downloaded the sample and it looks great. Now I just need an iPad of my own) rather than a cheap PDF (which would have taken then two minutes to make).
Also, I hope they incorporated the errata and included the FAQ. And that this way they can release an expanded SoB dex. Wouldn't that be nice?