Oppenheimer obviously also appears in Richard Rhodes' utterly superb "The Making of the Atomic Bomb", though he only becomes a main character in the sequel, "Dark Sun: The Making of the Hydrogen Bomb", which is also great.
Oppenheimer was a highly skilled physicist, but Rhodes attributes his ability to lead the Manhattan Project to his gifts as a "synthesizer" of ideas and knowledge from many people and disparate branches of science. In my opinion he really came into his own, though, after the bomb, when he started formulating the US' atomic energy strategy, essentially inserting himself -- a scientist, not a statesman -- into the political elite by sheer force of will and charisma. Rhodes tells of Oppenheimer completely dominating meetings in early efforts that resulted in the formation of the Atomic Energy Commission (which became the US Department of Energy), essentially writing national policy recommendations on his own.
Oppenheimer realized the dangers of nuclear proliferation and detente early on, and wanted the world to own atomic energy as a force for good. He wanted an international organization (what became the IAEA) to control atomic energy and not let the US and UK have a monopoly on it. Oppenheimer also recommended against developing the hydrogen bomb, which he thought would dangerously escalate the destructive power of nuclear arms. This opposition ultimately led to Oppeheimer's trial that cost him his security clearance.
But it was his extensive writings on what the future of atomic energy could be that I think set him apart in this years. He was prescient about nuclear arms race and tried to steer the US and the world towards peaceful use of atomic energy. If his policies had been implemented we may have been in a different place today.