Power on paper mean nothing for instance :
PS4 has always-on video compression and decompression systems for the purpose of video sharing and streaming which is great but,
it's not a costless process and, correct me if i'm wrong, but video compression is a realy demanding process.
I do not know which codec the ps4 is using for it and how efficient it is but the cost of it directly cut through the ps4's advantage over the Xbox One.
in fact, the higher the frame rate/ resolution of a game is, the higher the compression cost will be and this means that more a dev raise the frame rate / resolution of its game he litteraly will have less ressource to do it.
It is maybe one reason why Sony has announced that the ps4 will not support 4k gaming for now while microsoft annouced that nothing is blocking a dev from using 4k graphics in a game on Xbox One.
So even if on paper the ps4 has a great advantage the final result may be far from it and for what we've seen at e3, upcoming ps4 games are nowhere near as 2x better than those of xbox One.
the only true and well defined advantage of the ps4 is for now its price.