Physical Deck: 35 Cards, Plastic Container, Room for expansion, 8 UKP.
iPhone Deck: All the psychic powers, add photos, rules for force weapons, potential to expand perhaps to new codex powers, 8 UKP (well, 7.99 really).
For the moment, the virtual product price is not quite low enough for me (personally). It depends on how / if it is updated in the future really. But to be fair, about the only thing I want online is my army list(s) to consult during games at the moment. The physical codex and rulebook still work well for the game and I need to be convinced that swapping to a digital format results in positive gains. Perhaps the key is to make all of these digital products fully searchable and indexed thoroughly (very thoroughly). Still, as BoLS points out: it seems that going digital is the future option for GW. I trust they'll work hard to get this transition done and done well!