I find it funny how many people think NSA is "breaking the law", yet the majority of those FISA federal judges disagree. To some random people on the internet with no law experience or education, it's clear it's illegal, yet to professionals it's not. Hmm, I wonder which carries more weight.
Oh, well, now that I know the secret court issuing secret orders has approved of something, then that settles it. It's legal and obviously we shouldn't question those secret orders we can't know about! Glad you cleared that up.
Besides, there are obviously solid mechanisms to ensure the NSA et al are complying with the secret orders of the secret court. Whistleblowers that go to the press are prosecuted and charged under the espionage act, which carries the death penalty. Manning was held in punitive solitary confinement for months, against the advice of physicians, and cut off from the world. The press that reports on their leaks are threatened with jail if they don't reveal their sources, which has, as intended, put a screeching halt on that type of reporting as journalists can no longer promise to protect sources because to do so means jail time. Reporters have had their phones tapped. Whistle blowers who tried to address things internally have hit brick walls at step one of the process, which is why several went public. So these ways of checking the spy agencies should work great, because all anyone has to lose if they come forward with wrongdoing is a life term in prison! And journalists just risk jail if they report on the leaks!
Congressional oversight should also be effective. Why, at least a half dozen can be read into the most secret programs. And of course they can't reveal anything of what they know - they can't even tell their fellow members of Congress. And when called to testify, we can be sure that the heads of the agencies will tell us the "least untruthful" answer possible! So, they'll lie as little as possible! I know that makes me feel better.
And when properly vetted members of Congress and their staffs with appropriate security clearances do investigate the spy agencies, the agencies will spy on them, removing documents that are inconvenient, causing Congress to print the document, and carry it out in secret, and store in a damn safe to make sure they can have continued access to it. Which is a good thing because the document was disappeared from the electronic records. So the agencies have shown contempt for Congress and their oversight role, which means we should trust that Congress can effectively oversee these agencies.
In short, there is no worries I can see. It's legal, the secret court issues secret orders telling us so, and all the oversight mechanisms appear to be working fine.