You are currently required to have a paper based copy of the appropriate charts required for the flight. An iPad does not meet this requirement.
You are not required to have a paper based copy of the weather or notams - you are required to obtain a forecast, you are not required to keep it, so an iPad can meet this requirement.
While a moving map is nice, the GPS in the iPad is not TSO'd and can not be used for primary or sole means navigation.