Some shows generate buzz, and then there's The Book of Mormon. Riding into the West End on a juggernaut of hype and hysteria - even the Prime Minister's been spotted in previews - the big question is how can it possibly live up to expectations?

Well, it does. Largely. And how refreshing it is to see a show on a West End stage that resonates so widely across the cultural spectrum - on the night I saw it (a preview rather than tonight's gala opening), the excitement and enthusiasm in the stalls was of a kind I've not experienced before.

Like many great shows, Mormon (or should that be Mormnnn) was stuck in 'development hell' for several years before reaching the stage. The added time shows; there's very little wastage and creators Matt Stone and Trey Parker (in collaboration with Avenue Q composer Robert Lopez), who are used to turning around South Park episodes in a matter of days, have been given room to craft something with real artistic and musical weight.

The plot centres on two young Mormon missionaries, Elders Price and Cunningham (Gavin Creel and Jared Gertner, pictured), who have the unenviable task of spreading the word of Joseph Smith Jr, sorry, Jesus, in Uganda. Naturally their Lion King fantasies prove rather wide of the mark, and they're soon faced with the realities of scorching heat, a rampant Aids epidemic and a filthily-monikered circumcising warlord (Chris Jarman).

Without wishing to ruin the many surprises of the score, I can say that you're likely to be tickled by numbers including "Turn It Off", in which the Mormon missionaries describe how they deal with life's traumas, and "Baptize Me", where Elder Cunningham flirts with love interest Nabalungi (Alexia Khadime) using more double entendres than a Benny Hill sketch.

But the real show-stopper is "I Believe", where Creel - almost unrecognisable from his last appearance in the West End as Claude in Hair - bursts into a ballad of soaring Disney-fied magnificence as he decides to heal the genocidal warlord's ways with a faith founded on the premise that ancient Israelites travelled to America.

Not every number hits the mark - notably "Spooky Mormon Hell Dream", which is a derivation too far (not least of Parker and Stone's own work in the South Park movie) and adds little by way of narrative progression - but in the main this is a cornucopia of comedy musical treats.

Creel and Gertner, who have been brought over for the West End opening from the US tour, seem unmatchable as the mismatched missionaries, giving performances of enormous energy, wit and technical skill. And they're ably supported by the British contingent, including Stephen Ashfield stealing many of the biggest laughs as the closeted Elder McKinley and Giles Terera as a hopeful-against-the-odds Ugandan villager.

Co-director Casey Nicholaw's witty choreography matches the pin-sharp nature of the material, while designer Scott Pask serves up a slick and often humorously coarse series of settings. And the band (under musical director Nicolas Finlow) is one of the best you'll hear in a West End pit.

It will be fascinating to read the range of responses to Mormon - my hunch is they will fall squarely into the love or hate camps (the latter largely influenced by the strength of the religious satire). But for me and my generation, reared on South Park and Team America, there is little here to genuinely shock, and laughs by the bucketload.

If anything, by warm-heartedly embracing the medium of musical theatre, Parker and Stone have revealed a maturity and sensitivity lacking from their screen work. And I for one am delighted to welcome them to the fold.