According to an NSA official quoted by The Wall Street Journal, the leaks have been "cataclysmic" for the organization and forced a large-scale reevaluation of their policies. They were so devastating that General Keith Alexander offered to resign from his position as head of the NSA after Snowden came forward about the agency's domestic surveillance.
Eventually, Alexander retained his position, for a number of reasons:
When the leaks began, some top administration officials found their confidence in Gen. Alexander shaken because he presided over a grave security lapse, a former senior defense official said. But the officials also didn't think his resignation would solve the security problem and were concerned that letting him leave would wrongly hand Mr. Snowden a win, the former defense official said.
Along with the offered resignation, the agency suspended some of their monitoring programs—specifically among foreign leaders—and the events gave more credence to the belief that a civilian should head the NSA after Alexander steps down next spring, as he has been planning to do for a while. The expiration of Section 215 of the Patriot Act in a year and a half will also likely catalyze policy changes.
Part of the frustration over is that many of the NSA's activities are dictated by other departments of the government (for example, the NSA claims that their monitoring of Angela Merkel came at the behest of the State Department). According to one official, the NSA currently has 36,000 pages of intelligence requests from other agencies to be fulfilled.