Five stars (and if he scores lower than some idiot like Taft or Polk, well this forum is stupid)
Ask yourself this. Was the United States' position in the world stronger or weaker after a Polk Presidency than before it? And was the US's position stronger or weaker now or before Obama was president (protip: it's weaker). I would have been a Whig if I were born in that time/place, but Polk was anything but an idiot.
Well, with Polk the lives of many thousands of Mexicans wiped out and the nation was brought ever closer to Civil War, so I would say weaker.
And Obama? When he cam to power, the U.S. was considered a reckless, arrogant and wasteful empire; with shot alliances with traditional friends and enemies coming out of the wazoo. It's hard to be at a worse point than that.
Complaining about western foreign policy is rather odd. By and large, the spooks do what they want regardless of who is in charge; and they have done so since the Truman administration. Obama has been relatively hard on the intelligence agencies, and the ones he has been soft on are ones I don't care about anyway (PRISM and the NSA is such a yawnworthy scandal, IMO). I would love for a President to come out and say "the gulf states are a bunch of useless craps that murder their own civilians", but I think it's bad form to rate badly for what a President didn't do (for the most part anyway). Otherwise every PResident before Lincoln would be one star for not abolishing slavery etc.