We've learned a lot about the methods/programs NSA uses to collect information: metadata, PRISM, XKeyscore, etc. Its true that all of them provide fertile ground for the potential of abuse by the government. What we haven't learned about are any actual examples of abuse.
Its true that last August Bart Gellman reported that an internal NSA audit found that there were "thousands of 'incidents' or violations of the rules or court orders" under which the agency operates. But there is a significant difference between operator/typographical/computer errors and abuse. That report contained nothing to document the latter.
Recently Glenn Greenwald attempted to demonstrate abuse by reporting on five Muslim leaders the FBI and NSA spied on. But he failed to provide two pieces of important data that might have indicated there is an actual problem with abuse. First of all, he doesn't know whether or not the court approved warrants for this surveillance and if so, why.
Given that the government’s justifications for subjecting Gill and the other U.S. citizens to surveillance remain classified, it is impossible to know why their emails were monitored, or the extent of the surveillance. It is also unclear under what legal authority it was conducted, whether the men were formally targeted under FISA warrants, and what, if anything, authorities found that permitted them to continue spying on the men for prolonged periods of time.I almost laughed out loud when I read that first sentence. Here is Greenwald reporting on millions (?) of documents Snowden stole that were formerly classified. And yet he claims that he can't report on the reasons these men were surveilled because that information is classified. IOW, Snowden didn't manage to steal any documents that would tell us why.
Secondly, the spreadsheet Greenwald uses to demonstrate this surveillance indicates that it was terminated for two of the individuals in 2008 and extended for 3 of them about the same time. After that...nothing. So the surveillance he reported on occurred prior to that time (under the Bush administration) and he provided zero evidence that it continued beyond that date. I'll simply note that the Foreign Intelligence Surveillance Act was amended by Congress in July 2008. Whether or not this is why the spreadsheet contains no further information, we don't know. What we can be sure of is that if Snowden's documents contained proof that this surveillance had continued into the Obama administration, Greenwald would certainly have reported that.
In the end I'd suggest that what hasn't been reported is probably more important than what has been. We've just witnessed the biggest breach of national security secrets in our country's history. And after over a year of reporting, we have not seen one case of abuse documented. That's a pretty BFD.
So it is appropriate to question whether or not we are comfortable with the potential for abuse that these NSA programs make possible for future administrations. But other than the Bush administration's warrantless wiretapping that was reported by the NYT in 2005 (and ended in 2007), the Snowden documents have provided zero evidence of illegal surveillance or abuse.