You might want to take a look at Walter Russell Mead’s assessment of Hillary Clinton’s tenure as Secretary of State over at the Washington Post. I found it quite fair and even-handed. Here’s a sample:
How did Clinton understand the interplay of America’s power, its interests, its resources and its values? Was she able to translate that vision into policies that won enough support throughout the government to be carried out? Was she able to gain or keep the president’s confidence, and was the State Department under her leadership able to hold its own in the bureaucratic battles of the day? To the extent that her policy ideas were adopted, how effective were they? How well did she manage on the inevitable occasions when things went horribly wrong?
The quick synopsis of Dr. Mead’s assessment is that Sec. Clinton is an optimistic realist (Hamiltonian) with a strong global meliorist streak, unlike many foreign policy realists. What that means stripped of jargon is that she believes in pursuing American interests through “sea power, commercial expansion and a focus on strategic theaters in world politics” and that she believes that we have an obligation to use our power and influence to make the world a better place. Since I incline towards being a pessimistic idealist with a strong non-interventionist streak, you can hardly be farther from my views than she.
As to how well she held the office, Dr. Mead thinks she was a middling Secretary of State—better than some, not a titan of the office:
Historians will probably consider Clinton significantly more successful than run-of-the-mill secretaries of state such as James G. Blaine or the long-serving Cordell Hull, but don’t expect to see her on a pedestal with Dean Acheson or John Quincy Adams anytime soon.