Two main obstacles must have faced Ronald Harwood when preparing material on Gustav Mahler for the stage. Firstly, how to portray the grand sweep of a composer's career without the full battalion of an orchestra arrayed on stage. Secondly, how to interest a contemporary audience in the fate of an artist who was cold-shouldered for much of his lifetime, and is still met with indifferent shrugs by many classical luminaries today.

Harwood overcomes the first by injecting brief blasts of Mahler's work into the constant stream of scene changes. Whether or not he has surmounted the second challenge must remain a matter of opinion, although a dazzling cast do their level best with the fleshy and feisty material on offer.

When we first meet Mahler, depicted with typical dexterity by Antony Sher, he is struggling with matters of conscience and conversion. A top composer's job in the Vienna Court awaits him if he can be persuaded to deny his Jewish ancestry and convert to Catholicism. Nickolas Grace, suave and dazzling as Siegfried Lipiner, informs us that intrigue has displaced coffee as Vienna's favoured beverage. 'Mocha has been replaced by Mahler,' he informs the assembled aesthetes with glee.

However, Mahler's beliefs seem to confound him as much as the puzzled priest who is sent to convert him. Sher, his voice almost constricted with the emotion of Mahler's rampantly vibrant persona, rages and wrestles with life as its demands on him increase. All the while, Stephen Brimson Lewis' intriguing setting demands a case study all if its own. A black leather couch waits by, as if to cater for Mahler's sexual promiscuity or invite him down for analysis as a tormented patient.

Indeed, it comes as no real surprise when Sigmund Freud makes a notable cameo in the assured hands of Gary Waldhorn. This provides the longest scene of the night, amid a bustle of shorter scenarios which eventually offer too many possibilities. How much more insightful Harwood could have been by just homing in on one particular chapter of Mahler's life and giving it the full cross-examination.

Sher's performance is predictably potent, with the full range of gestures, inflections and accents well in command. He reveals a man made ecstatic by wild creation and ultimately laid low by the folly of love. But you wind up asking whether Harwood intends you to sympathise or empathise with his protagonist - or even to despise him.

Theories and ideologies rain on the audience throughout as if the author intends to conduct a storm of knowledge from the heavens. And rather too many orchestral manoeuvres in the Aldwych dark leave this symphony somewhat in need of greater harmony.

- Gareth Thompson