It's almost over.

True, this year's Edinburgh Festival has a colossal final day of concerts today, beginning in the morning and running right through the evening. And even then you might argue that it ain't over until Garry Walker and the Scottish Chamber Orchestra, with the assistance of an arsenal of explosives, paint the Edinburgh skyline tomorrow night at the annual Fireworks Concert.

But in one respect this year's festival is already done. Festival director Jonathan Mills (this is possibly the last time I can refer to him as such) has finished his work, completed his contract, and will now demit his post. I have a personal reflection on his period of tenure that I would like on record.

Mills has had a terrible slagging from certain quarters, even to the extent of him failing to understand what the festival is all about. I've never bothered with, or replied to, any of this stuff. I've been around long enough to realise that it is sufficient to smile and turn to stone while acknowledging privately that naked prejudice is impenetrable philistinism, and is a complete waste of time; and anyway, life is too short and energy too scarce and precious to spend one second of one's time entertaining the culturally myopic.

It seems to me that Mills has left the big flagship series at the Usher Hall and Queen's Hall in a decent state. Of course we will argue from now until kingdom come about his choice of this orchestra or that, this conductor or that one, and endlessly debate the merits or failures of programme content which, I have noticed among Mills's detractors, almost always circles exclusively around personal taste. And I have often suspected that the worn-out charge "I don't think this is appropriate music for such a grand, festive occasion as the Edinburgh Festival" actually translates as "I don't know this music, therefore I don't like it".

There are some incredibly knowledgeable, diehard music lovers out there. But, you know, I suspect there are some clowns and clots, too.

Mills's legacy, for me, and therefore an inheritance for his successor, is the sheer depth and breadth of musical experiences that he has served up for the genuinely curious among us. Do you remember early perceptions of his strategy? That what he was going to do was address major gaps in the festival's musical provision? That boiled down to this: Mills's predecessor, Brian McMaster, didn't like Baroque music, therefore it didn't get programmed.

That was very quickly addressed and the breadth of programming grew rapidly. But Mills went much further than that, way back before the recognised time of the early beginnings of western musical development, right down into the roots of music, way beneath the soil, right across continents and into radically different cultures.

And he was still doing that right to the end, as we heard in two very different presentations this year in the Greyfriars Kirk series, from the amazing Chinese artists Wu Man and Sanubar Tursun, and from that extraordinary Lebanese nun, Sister Marie Keyrouz, whose voice and music shook my soul to the core. Music is not just what we know already; not just something else from an already-familiar tradition: this was adventurism, education, exploration and, yes, entertainment, all wrapped up in one brilliant, bracing package.

And that package has a name; and the name is Greyfriars Kirk. Nobody who has been near the place this year has failed to fall under its spell. It used to be regarded as peripheral, marginal even. It's a new core within the festival. It housed comfortably every brand and species of music from ancient to modern, from choral to chamber music and all points in between.

It is a very, very special venue, now has an ethos all its own. And, by the way, it has a unique, fully-engaged audience too. I saw them all this year, talked to many in that now-famous Greyfriars queue, and they all have one thing in common: they are Real Listeners. That's Jonathan Mills's work.