When Harry Met Sally, Theatre Royal, Haymarket, London

Shallow and meretricious though the 1989 movie may have been, Marcy Kahan's adaptation makes the original When Harry Met Sally look like a Heidegger-Kant co-production. On a stage that has been turned into a wide-screen TV, this anorexic love story isn't even on a par with the average sitcom: it's just a string of commercials for true lurve.

For some time, romantic comedy has been a floundering film genre, largely because of the failure of writers to cast a rosy glow over our erotic culture of instant gratification. Nora Ephron's solution was a mechanical one: have the couple meet not once but several times over more than a decade, prevented from hitting the sack by being otherwise engaged or by a vow of chaste friendship. When they finally get it on, the event is earth-shattering for Harry because, for once, he is making love to a woman he already knows and likes. The sex breaks the Richter scale for Sally, too, perhaps because of the finesse Harry has acquired from considerable experience: he regularly tells Sally of the many women he loves and leaves - assuring her and us that, in marrying a guy who has been hanging around for years, she is not settling for a loser. She might, of course - but doesn't - ask herself if Harry's promiscuity is his angry way of compensating for his failure to compete successfully with men. "I'm not ruthless," he says sadly, turning his being passed over for promotion into a character reference.

It's hard to believe, though, that the aimless Harry and the chirpy Sally, who, in their thirties, look and sound like teenagers, have any jobs at all. Luke Perry and Alyson Hannigan are as convincing a lawyer and reporter as their milieu (a few other young, pretty white people in a glaringly white box) is a convincing representation of New York. Sally has no interests besides housekeeping, and no idiosyncrasies beyond a tiresome fussiness about food (when Harry finally tells her what makes her lovable, he is reduced to saying that she takes an hour and a half to order in restaurants).

Loveday Ingram's charmless production botches even the movie's most famous gag. As Sally fakes orgasm in a coffee shop, a table of young men grin in lubricious delight. The punchline is not given to an old lady keen on her food, but to one of the leering chaps, and his order of "what she's having" is the less funny for being a joke.

As if it weren't shameless enough on its own, the play is punctuated by films of elderly couples relating how they met. One twosome is black, one is gay, but all are educated, prosperous and tastefully dressed. It's typical of the materialistic, immature vision of this show that love is portrayed, like a two-bedroom apartment and a creative but well-paid job, as something every pleasant, upper-middle-class woman deserves. As the aristocratic lady exclaimed after her first time in bed with a man: "Do the lower classes do this too? It's far too good for them!"

To 29 May (020-7930 8800)