Who presents a great threat to individual liberty? The people that the NSA are using this program to 'protect us' from, or an all seeing, all knowing government?
I think history shows us that abusive and unaccountable governments have caused far more harm than individual terrorists ever could do.
I don't think this program is the only way to protect us either.
Given a choice, I think I'd take my chances with the lone wolf criminal rather than the anonymous all-knowing government bureaucrat.