Departing national security affairs adviser Robert C. (Bud) McFarlane, the quiet center of many stormy disputes in the Reagan administration, leaves the White House with a mixed legacy.

Administration and congressional sources who evaluated McFarlane's performance in a pressure-cooker post yesterday gave him high marks for crisis management, mastery of complex arms control issues and especially for persuading President Reagan to undertake a series of summit meetings with Soviet leader Mikhail Gorbachev.

They also say that McFarlane, drawing on his background as a Senate staff member, dealt more effectively with Congress than his predecessors or senior colleagues.

But for all these successes, McFarlane failed in his effort to achieve a dramatic breakthrough in arms control policy that called for the president to limit his missile defense plan, the Strategic Defense Initiative (SDI), in return for Soviet acceptance of deep reductions in offensive nuclear weaponry.

During two difficult years as Reagan's principal foreign policy adviser, McFarlane also proved unable to control, though he succeeded in curbing, persistent feuding between the administration's most powerful Cabinet members: Defense Secretary Caspar W. Weinberger and Secretary of State George P. Shultz.

Some say that McFarlane's influence was limited, despite his grasp of the issues, because of a structure he inherited which subordinated the national security adviser to the Cabinet secretaries, and even more because he never became what one official called "a member of the fraternity."

McFarlane was an official who briefed Reagan every morning -- an aide, not a pal. His predecessor, William P. Clark, far less knowledgeable in foreign affairs, has been a friend and trouble-shooter for Reagan throughout his political career.

Shultz and Weinberger, whose relationships with Reagan also go back to California days, and White House chief of staff Donald T. Regan are presidential peers who fit well into the old-boy atmosphere of the White House and enjoy swapping stories with Reagan.

In contrast, the soft-spoken McFarlane, once a member of Henry A. Kissinger's staff, seemed professorial to Reagan, who usually prefers an anecdotal discussion of policy to technical dissertations.

Given these shortcomings for the job at hand, McFarlane achieved far more than most colleagues thought possible when he arrived at the White House as Clark's deputy in 1981.

An insider at the time described McFarlane, a Marine combat veteran of the Vietnam war, as "the perfect No. 2 man, or maybe No. 2 1/2."

But McFarlane proved to have staying power and ability.

When the pressures prompted Clark to leave in October 1983, McFarlane took over and became the guiding hand for the administration in its efforts to win approval of the MX intercontinental ballistic missile and other controversial weapons systems.

"The Congress had great confidence in Bud McFarlane's judgments and his ability to understand what was politically doable on Capitol Hill while at the same time consistent with Reagan policy," said Kenneth M. Duberstein, the former chief legislative liaison for the White House.

Rep. Les Aspin (D-Wis.), chairman of the House Armed Services Committee, earlier this year credited McFarlane with "breaking the arms control gridlock" because of his understanding of political realities in Congress.

On most issues, McFarlane also understood the political realities in the administration. While he sided more often than not with Shultz, McFarlane won the reputation of an honest broker who tried to consider the interests of all sides.

Assistant Secretary of Defense Richard N. Perle, who differed with McFarlane on many issues, praised him yesterday as "fair and balanced" in his decisions.

Some officials said that McFarlane was the only senior official in the administration who could match Perle -- a frequent foe of arms control -- in knowledge of nuclear weaponry.

Yesterday, an emotional McFarlane took leave of the administration with the praise of the president and other high officials ringing in his ears. Reagan cited McFarlane's "key role" in the Geneva summit and "in carrying out our counterterrorism policies, as exemplified by the TWA hijacking incident and our recent operation leading to the apprehension of the hijackers of the Achille Lauro."

Shultz said that "the American people and people all around the world who care about peace and freedom . . . owe a great debt of gratitude to Bud McFarlane."

Former secretary of state Kissinger, in Detroit for a speech, said that McFarlane's departure was "a loss to the country" and could cause problems in preparing for the next superpower summit.

Nancy Reagan, who had grown to like and respect McFarlane, said of him, "I'll miss him, wish him well."

McFarlane, red-eyed and tight-lipped as he read a prepared statement, told Reagan that after 30 years of government service "I can only say how deeply grateful I am for the honor and privilege that you have bestowed upon me to serve at this time."