While I don't disagree that it is a strong political move, and an appropriate one, I have seen no proof that any of the NSA's operations have made the USA materially safer.
Everybody else? Something about eating cake, I think...
Like I said, the difference in actual security here is abstract, difficult to quantify, and potentially nothing practically speaking.
there has been no attack - look at how good we're doing our job of protecting you. but just to be sure, we need more surveillance.
there has been an attack -see! the NSA can't even prevent single incident X and are doing NOTHING to protect us!
there hasn't been a large scale terrorist attack in north america in 13 1/2 years -there is no evidence that NSA is doing anything to protect America!
0 in 13.5 years is not (especially considering that "large scale terrorist attacks" can only occur in integer units) substantially below the long-run historical average.
So, yeah, that, in and of itself, is not really any kind of evidence of any success of any changed policy since the last attack.
When someone says "the NSA couldn't even stop the Boston Marathon bombing", they are implying that the NSA SHOULD have been able to. But for the NSA to be able to stop it, they would have to be collecting data on US citizens inside the USA.
You can't have it both ways. You can't blast the NSA for not being able to stop Boston but then also be against them doing domestic collection. The fact that they couldn't stop Boston shows that they weren't spying on Americans (even though one was on watchlists).