Jerry Springer: The Opera, National Theatre, Lyttelton, London ***

Confessions of a dangerous kind

"Jer-ry!, Jer-ry!, Jer-ry!" Yes, at long last, after a build-up that leaves the Second Coming looking a mite underanticipated, Jerry Springer: the Opera hits the stage of the National Theatre.

With a score by Richard Thomas, who wrote the book and lyrics with the director, Stewart Lee, this show inaugurates the reign of the National's new head honcho, Nicholas Hytner. He duly demonstrates a skill that will prove very handy in this role: when you spot talent elsewhere, bring it in, nurture it and claim it as your own. The main hero of the enterprise, however, is Tom Morris, the impresario of Battersea Arts Centre, the enterprising outfit that acted as womb and midwife to this piece throughout its two-year gestation and various public try-outs.

Sung with a stunning range of vocal colours and open-throated passion by a terrific cast, the show camply plays on the outrageous similarities between confessional TV and opera. These range from the technical (people bellowing over each other, so you can't make out a damn word) to the thematic (a lava flow of primal emotion – jealousy, rage, fear, sexual confusion, et al).

It also, in a sustained blast of blasphemy, suggests that there's a link with religious rite. Jerry can be seen as God's representative on earth – a sort of high priest before whom sinners make ritual confessions, in the hope of the absolution given by 15 seconds of fame and Jerry's "final thought". So the mode of the piece is mostly mock-heroic, inviting us to savour the wacky incongruity of trailer-trash pouring forth their secret fears and desires in music more associated with mythic heroes, and to thrill to the cultural mismatch of hearing Jerry's on-stage audience express their freak-show schadenfreude in soaring Howells-like anthems. Only shrugging, buck-passing Jerry (nicely played by Michael Brandon) doesn't get to warble.

But you begin to worry, as you meet the guests – the "Chick with a Dick" and the enormous guy whose biggest thrill is to poop in his diapers etc etc – that the show is going to be a bit of a one-joke wonder. I'm very partial to bad taste and to the childish glee, say, of a loud fart in church. Too much, though, obeys a law of diminishing returns. As a check to this, there are some very powerful passages where unparodied, genuine feeling gushes out – as in, say, the Baroque, soaring, slightly country-style number where Alison Jiear's knockout Shawntel, a woman past her sell-by-date, reveals her yearning to be a sexy pole-dancer.

Bringing together Jerry Springer and opera offers, after all, the possibility of terrible tragedy as well as skittish satire and I could have done with a few more moments where that fact made itself felt. In Assassins, Stephen Sondheim brilliantly sustained the conceit that there was a telling overlap between the self-assertive ideology of the American musical and the impulse that led people to want to kill US presidents. By comparison with that, the connections made here between opera and lowbrow confessional culture feel clever, but somewhat underdeveloped.

At the close of the first half, Jerry is shot and, after the interval, we follow him to hell, where he is forced to host a show with the ultimate conflicting guests: Jesus and the Devil (who is looking for an apology). So as not to spoil the deliriously silly surprise ending, I will just cryptically say that it suggests that, like that other agony uncle, God, Jerry is absolutely everywhere.

Not a great show, but a heartening statement of intent by the Hytner regime. And what better place for a "Chick with a Dick" than in an opera with balls?

To 5 July (020-7452 3000)