The strongest man is he who stands alone, proclaims Ibsen's hero in An Enemy of the People. And sometimes the strangest, too. There's something exhilarating about not agreeing with anyone, as I discover yet again in my reaction to Kevin Spacey's Richard III.

I don't hate it. I don't not admire its energy and verve. I just find the performance predictable, one-note and very, very shouted. And of course I bow to no one in my admiration for Spacey as an actor. He is electrifying in almost everything else I've seen him do, on stage and screen.

We thought he was making a big mistake when he played Richard II directed by Trevor Nunn a few years ago. But he packed a big surprise in that one, finding whole areas of the play, and the character, that leapt to life because he wasn't going down the usual sanctimonious route. In an interesting and creative way, he played against the grain and found the grit.

Add another "I" and you think you know what to expect. And there it is: an upfront malevolent psychopath with a twisted torso and crippled leg burning like a brazier and mowing down all and sundry in the intensity of his laser-like penetration and aggression.

But he's not funny, he's not wheedling, he's not sly and he's not the black intelligencer of the text and other people's opinion. The scene where he accepts the crown after refusing it, acting like the maid of folklore who says No but means Yes, is dissipated through the theatre, with characters in the stalls, some on the stage and Spacey himself on film. The theatricality, black humour and, above all, speed of the sequence is entirely lost. (As indeed is the brilliant opening of the play, fudged with an interpolated film extract of Edward's coronation.)

I absolutely loved Sam Mendes' 1992 RSC touring production with Simon Russell Beale as an undercutting, slickly poisonous toad of a Richard, famously proclaimed by Paul Taylor as the unhappy result of a one-night stand between Pere Ubu and Gertrude Stein. Russell Beale gave momentum to the character by virtue of being a resentful and revengeful outsider. Spacey owns the shop, as he owns the stage, from the outset.

I'm uneasy, too, about the portrait of Richard as an all-purpose pariah tyrant, with clear visual references to Colonel Gaddafi, President Mubarak of Egypt and even Mussolini - this last as Spacey is strung up by his feet at the end.

The programme notes bang on a bit about Gaddafi and Mubarak, too. An exiled Iranian friend of mine was in London this week and was telling me how very low we British are now held in the estimation of ordinary people in the Arab world. The hunting down and humiliating executions of Saddam Hussein and Osama bin Laden have done our reputation as humane arbiters of justice and respecters of human dignity no good whatsoever.

But for years we approved and encouraged both Gaddafi and, especially, Mubarak. Now we've gone all pious and superior about them, however justifiably. And the sight of pampered liberal intellectuals like Sam Mendes with nothing to lose jumping on some politically mobilised band wagon, without understanding the global consequences, is frankly nauseating; to most ordinary Arabs in their coffee shops, at least.

Kevin Spacey himself probably approves the unauthorised execution of Osama bin Laden by his pal President Obama. Apart from the moral queasiness involved, he should stop and think about retaliation, and the future safety of passengers on American Airlines, which he advertises so assiduously on television.

The other thing about Richard III at the Old Vic is just how bad the supporting cast is. I am mystified by praise (admittedly muted) for Chuk Iwuji's Buckingham, who face-pulls blandly all evening and is memorable only for his extarordinary set of too-large flashing white teeth.

The less said about the American supporting actors the better - Clarence is totally incomprehensible, though Maureen Anderman as the Duchess of York is okay, just about. Our own Haydn Gwynne and Gemma Jones, as Queen Elizabeth and mad Margaret, do the best they can within the confines of a production that is short on ideas and long on bombast.

One idea, nicked from Bill Alexander's RSC revival with Antony Sher - now, there was a show, there was a Richard - is the coronation procession in a heavy ermine robe that ends the first act. But it doesn't have the same sickly impact as Sher's shuffle to the throne, the phsysical exposure, or that brilliant touch he added of breaking through the severe pain barrier of his deformity to seize the moment and the crown.