Most people were gobsmacked. Timon of Athens? Who ever heard of it? Turns out, it's a play about bad behaviour in the city, celebrity, mis-directed corporate hospitality, sponsorship, and a protest encampment. Had Nicholas Hytner and Simon Russell Beale (as the old curmudgeon) updated the play too much? Not at all. Not enough!

Metaphorically, I heard the sound of upturned benefactors' seats hitting the rail, as Timon smoothed his way through the opening scenes, preening himself at the equivalent of the new "Lloyd Dorfman" theatre (the soon to be re-named Cottesloe) as the "Timon" room.

Dorfman, of course, has been an exemplary NT sponsor and is singlehandedly responsible for the Travelex £12 ticket scheme of which this new Timon, ironically enough, is a part. How very post-modern of him to take Hytner's implicit criticism on the chin; or at least we presume he is doing so.

As always with this play, we were poised to dislike Timon intensely. He's the least attractive major character in the canon. Except that Russell Beale - through force of intellect alone - makes him so loveable. Which is not how I remember him at all in Paul Scofield's magnificently dismissive performance for the RSC, directed by John Schlesinger.

The audience last night included the writer and New Yorker critic John Lahr, who is writing a profile of Hytner which should be worth reading. He'd never seen the play before and couldn't remember when he was last at a NT first night.

"So, anything happening in New York?" I asked him. That took the wind out of his sails. "Oh, there's a really beautiful new theatre opening at the top of the Lincoln Center." "And what's going to happen there?" Floored him again.

Changing tack, he said I should go out of my way to see anything written by someone called Will Eno, no relation of Brian. And he cheered me up mightily by saying that he was just finishing (at last) his critical biography of Tennessee Williams. I told him about Vieux Carré at the King's Head and his eyes glazed over.

If I thought that was bad, had I ever seen The Red Devil Battery Sign, written around the same time in the late 1970s? I admitted that I had but preferred not to talk about it. That was the play in which Anthony Quinn told a New York preview audience that he would offer free tickets to anyone who felt cheated. They could come back and see it again later, when the piece was ready. No-one took up the offer.

Some people feel the same about Timon of Athens, but not after this new National production, I reckon. It was odd to see the play described in one newspaper listing as Shakespeare's "difficult" play, a term usually reserved for All's Well That Ends Well, or Troilus and Cressida, perhaps King John or, less often nowadays, Measure for Measure.

Timon isn't "difficult": rich bloke buys friendship, learns the error of his ways, turns against humanity, and that's it. "Only an incident with comments on it," said one early Victorian producer. Maybe the listings person meant to say "rarely performed"; but even that's no longer true, though it was when Scofield did it; like Russell Beale, only more so, he could join both halves of the play in his poetic incandescence.

Since Scofield, there's been Richard Pasco and Michael Pennington at the RSC, a wonderful production by Peter Brook in his early days at the Bouffes du Nord in Paris and David Suchet at the Young Vic in Trevor Nunn's revival. (A production in Canada even set the play in the 1920s, with Timon conceived as a figure akin to the Great Gatsby.)

So in modern times it's become a sort of parable of the catastrophe in capitalism, which is always a popular theme, rather than a personal tragedy. And the other thing, of course, is the attribution of many scenes in the play to Thomas Middleton; Gary Taylor even includes the play in his magisterial Collected Works of Middleton, commenting that we can now comfortably think of the play as adjacent both to Shakespeare's King Lear and Middleton's city plays of homosocial networks and ruthless creditors.

Hytner and Russell Beale certainly pursue the late twentieth century mild obsession with the play as a social satire. The posters resemble one of those "fake celebrity" Alison Jackson photographs, with clearly identifiable likenesses of David Beckham, Madonna and Boris Johnson crowding round Timon at his champagne-laden dining table.

J C Trewin described the play as Shakespeare's "loneliest" and the adjective is doubly just: the play does stand apart from the main core of the repertory. And Timon has no family, no lover, no relationship with anyone, and no women (apart from the whores).

Well, at the National, he does at least have women, notably Deborah Findlay as his long-suffering PA and Olivia Llewellyn as a city fixer. And the whores are re-cast as elegant ballet dancers, the after-dinner entertainment. There's quite a lot of fiddling around with the play, and some lines imported from other plays, but everything is for the best in this worst of all possible worlds.

There's something pure, stark and ineffable about the play which I love - Karl Marx professed it his favourite in all Shakespeare, because it's all about money and the decline of capitalism; and the great speeches in the second half, which Russell Beale somehow subsumes into the ramblings of a filthy old contemporary vagrant, are as great as any in the canon.

With SRB in the cast, and Hytner's production already selling fast on the cheap ticket scheme, it looks as though Timon's not going to be the "loneliest" play for too much longer.