First Night: The Lord Of The Rings, Theatre Royal, Drury Lane, London

Unless you've spent the past few months stuck in the Crack of Doom or down the mines of Moria, you'll be aware that this musical adaptation of Tolkien's The Lord of the Rings has cost £12.5m (making it one of the most expensive stage works on record) and that it failed to recoup its budget in Toronto where the world premiere last year had a mixed critical response.

Heavily revamped, and with 45 minutes lopped off its original three-hour running time, it opened last night at London's Theatre Royal, Drury Lane. Is it now the one show to rule them all?

I wonder what the Elvish word is for "no". The director, Matthew Warchus, maintains that he and the creative team "have not attempted to pull the novel towards the standard conventions of musical theatre, but rather to expand those conventions so that they will accommodate Tolkien's material". That is commendable. The average musical is a boy-meets-girl affair, and sexual desire is barely on the agenda in the Tolkien world, where no one is ever going to ask "Did Middle Earth move for you, darling?"

But the promised "hybrid of text, physical theatre, music and spectacle never previously seen on this scale" turns out to be a show with a bit of an identity crisis, strong on dynamic spectacle, squeezed as drama, and in two minds about how it wants to use music dramatically.

The score, by the Bollywood composer A R Rahman, the Finnish group Varttina and the show's musical supervisor, Christopher Nightingale, is a pleasingly plangent mix of the folky and the mystical, Enya meets Riverdance. Especially when Laura Michelle Kelly's Galadriel lets rip with eerie crystalline clarity and Celtic-tinged melodic curlicues, it can create a magical, otherworldly atmosphere that combines ethnic strangeness with elegiac lament for the passing of an era.

But I find it disappointing that the music is employed as an accompaniment to the drama (characters tend to sing when it would be natural to do so, to bestow ceremonial blessings, keep their spirits up, or when joining forces for a jamboree or a battle) rather than as a way of digging deeper into it.

And if the show is prepared to break its own logic by allowing Aragorn and Arwen a drippy, pop-opera love song, why can't it let music explore and lend urgency to the moral disputes and dilemmas that surface as it follows the hobbit Frodo (an engaging, fresh-faced James Loye) on his mission to destroy the evil ring?

With epic, it's vital to get a sense of time passed, distance covered and suffering endured. Here, despite the drastic cuts to material, it took three lengthy films to encompass, the story-telling is rushed. Some of the ordeals seem to be over almost before they've begun, so it's hard for the adventures to register the requisite weight. The evening's stand-out performer is Michael Thierriault who jerks and jack-knifes like an addict assailed by painful, conflicting impulses as the slimy, perverted Gollum. Even a fine classical actor, Malcolm Storry, who plays Gandalf, is left struggling with cardboard characterisation.

Rob Howell's design, thrillingly lit by Paul Pyant, sends a creepy canopy of twisted tree roots out into the auditorium. There are levitating elves, vertiginously stilted Ents, and rabid, leather-clad Orcs on curved pogo-sticks and sinister crutches who, deterring any plan to leave during the short second interval, run amok amongst the punters and hiss at them through scary teeth.

The gigantic, spitting Shelob will be a major recruiting drive for arachnophobia. But is impressive spectacle sufficient compensation for other inadequacies? When Gandalf is attacked by the demon, Balrog, an almighty wind gusts through the theatre. Viewed as a piece of music drama, this show is unlikely to blow you away.