Pilots get to use iPads for the whole flight, but passengers don't.

From F.A.A. Approves iPads in Cockpits, but Not for Passengers:

There is some thought that the rule forbidding devices during takeoff and landing was made to ensure that passengers paid attention. The F.A.A. has never claimed this. (If this was the case, passengers would not be allowed to have books, magazines or newspapers during takeoff and landing.)