The Xbox One has ten times the power of the Xbox 360, before considering the power that can be brought to bear using the power of the cloud on the backend. The ten times number really only is a comparison of the local machine’s computing functionality when compared to the Xbox 360.
The use of cloud computing on the backend is a real game changer, because by using these servers in the cloud a massive amount of power can be available to open an interesting amount of possibilities. Of course, you need to be connected to access the computing power that is available to the Xbox One in the cloud. It is too early to say how developers will use this additional processing power, but both Forza 5 and Titanfall are examples of Xbox One titles that will use the power of the cloud as part of their games.