Although I classify myself as a libertarian, I have not been a big fan of Rand Paul, and even less so of his father (whose crank persona, in my opinion, was very damaging to the libertarian cause).
But he deserves great credit for his stand against the use of drones against US citizens in the US. It is terrifying that the Attorney General could say that the president could do such a thing, and great that Paul's filibuster made him back down and 'clarify' his statement.
What is disgusting (and frightening) is that a high official such as the AG could take such a position in the first place, and that so few people other than Paul had the courage to speak out.
There is a tendency by both parties to adopt the view that the president can do any damn thing he pleases -- at least when the incumbent is a member of their party. What they forget is that the expanded powers they support will be used by the next president, and will almost certainly be further expanded. The silence of most Democrats, many of whom pose as defenders of civil liberties, was criminal; but many Republicans also kept their silence (or opposed Paul -- I'm looking at you, John McCain), and almost all supported similar expansions of presidential power during the Bush Administration.
Holder was forced to back down -- this time. But the steady advance of the Imperial Presidency will continue, I suspect.