I've downloaded the sample to try out and I'd say it looks an improvement over the first Space Marine codex. Layout looks a lot better and it seems to explain its features better.
I'll more than likely get this at some point in the future as well as the actual book. I prefer hard copies, but feel that it would be easier to use, especially with travel to and from Uni. Though at the price, it probably wont be for some time.
I've taken some screen shots that show off the features of it:
Introduction of how the book works:
Model showcase with 360' view
Model showcase with gallery and 360' view
Model gallery expanded
Hope that helps show it to those of you with out iPads as I think GW only made videos for the Space Marine release.