This will not be a fully thought out discussion of William F. Buckley's influence and achievements. For a bit more in that direction, see this review of a Buckley bio and this review of a book on National Review's history.
There is a lot I could disagree with about the way Buckley treated what he clearly thought of as his conservative movement throughout the years, particularly his linking it with an endless war against communists both domestic and foreign. But I should also remember that if the conservative movement of today were more truly his, it would be a conservative movement I could cheer far more than I can the one we are actually faced with here in the phenomenal world Buckley has just left us behind in.
On the passing of this man of world-historical importance, I prefer to just note some details of his charm and humanity. He is known as a ruthless enforcer of orthodoxy within conservatism (for his own extended take on why he felt he had to be, see his 2003 novel Getting It Right in which fictionalized Objectivists and Birchers are drubbed). He's cheered for it and booed for it by different camps for different reasons.
But in his personal life, for the most part, he showed a winning ability (again, much of the time, not all) to be friendly and supportive beyond obvious ideological differences. I prefer to remember the Buckley who is understood to have provided support above and beyond the call to such friends and mentors as Whittaker Chambers and aging anarchist Frank Chodorov in his waning years; who could write, in response to many intemperate attack letters from his old buddy Murray Rothbard that "not that I love you any the less, you perverse old anarchist. But don't worry, when the Communists come, I'll run interference"; who would publish articles by the then utterly disreputable Timothy Leary in National Review in 1976 based on what Leary told me was the intertangled old acquaintanceships between his New England Irish aunts and Buckley's family, and "out of friendship–libertarian friendship"; and the man who could be long and intimate pals with ideologues who he considered as dangerous and wrong as John Kenneth Galbraith.
He was often a sterling example of letting humane considerations trump political ones (though he was usually less charitable toward ones, like Rothbard, Garry Wills, or Joseph Sobran, who he had thought of as "on his side" but who then shifted in whatever direction).
Yes, this kind forbearance was not universal, and some of his own obituaries for prominent libertarians he was at odds with such as Rand and Rothbard were intemperate. A complicated man, to be sure, and a complicated public influence. But on this day of his passing, I'll remember the wit who wrote an amused but delicate letter trying to placate F.A. Hayek (who was appalled at the indecorum of running a gag item hinting that deceased UN chief Dag Hammarskjold had cheated at cards); and who wrote in his influential column in 1971–the year that radical libertarians like Louis Rossetto were on the front page of the New York Times Sunday Magazine–that "the radical libertarians have a great deal to contribute."