Personally, I have mixed feelings about the program. While we have government assurances that the program is limited in scope, does not target US citizens, and is under close supervision, I'm not sure that I'm completely comforted by that. Rules governing use are hard to enforce, particularly when cloaked in complete secrecy. So, I think that any program like this can be easily misused, which clearly concerns me.
At the same time, on a practical level, do we not expect our intelligence community to use information and technology in their efforts to keep us safe? Whether it's the Boston bombing or Benghazi, there's a fairly strong outcry asking "how come our intelligence efforts couldn't prevent this"?
Following 9/11, I worked for a company that provided semantic technology used to identify potential relationships between entities. While they were not our primary market, the Intelligence Community quickly saw value in what we did, and our product was part of the Poindexter-led Total Information Awareness ("TIA") project. TIA was clearly a bit in-your-face (the all-seeing eye of God was a bit much, not to mention hiring John Poindexter to oversee the effort) and the program was officially killed in 2003 when Congress refused to fund it. But the program never died. Our software licenses were simply shifted to a different project, with different funding, but where the same analysts were the users.
Technology has come a long way in ten years. Entity extraction, data mining and analytics are commonplace tools in the business environment. It shouldn't shock anyone to see those tools are used by our government agencies, particularly the one tasked with "signal intelligence".
Accessing voice, email and social media data takes that to another level. And I think it's good that we're having this public debate. Personally, I am very conflicted about this issue. But many of those now voicing the loudest criticism will be among those asking "how did we not know about this" when the next incident occurs.