Monumental in scale and scope, Götterdämmerung is a work to which it is hard to be indifferent. For many, the idea of an evening of fantasy opera lasting nearly seven hours is unimaginable, so uncongenial is the subject material and so great the attention span demanded. For Wagner fans - and Ring fans in particular - it's a riveting theatrical and musical experience, the zenith of opera as an art form. Last night at Covent Garden was my first live Götterdämmerung, spent in the company of around three thousand of those fans.

The lead roles of Götterdämmerung are generally thought to be Siegfried and Brünnhilde, but on this occasion, there was no question in my mind who was running the show. John Tomlinson bossed the whole thing as Hagen, the scheming evil genius whose plotting results in the disasters at the end, and I've run out of superlatives. As an actor, he displayed schoolboy relish in the cleverness of his schemes, juxtaposed with the studious brilliance of the evil scientist and unbridled delight in Machiavellian manipulation of people. Vocally, Tomlinson's quality of timbre and command of dynamics and line were of the very highest, aided by sensitive conducting by Pappano which allowed Tomlinson's voice time and space to breathe.

If I had any doubts about Pappano and the Royal Opera Orchestra in last week's Walküre, these were dispelled last night. The intensity never flagged, without a single moment in five hours of music in which I felt anything other than totally engaged. The orchestral high point was Siegfried's funeral march, in which the repeated pairs of drum beats hit me like rifle shots, to the backing of that huge Wagnerian brass. But there was much playing to admire, from the dark strings in the opening to a multitude of woodwind quotes to the evocative calls of Siegfired's hunting horn to the sound of no less than six harps that accompany the Rhinemaidens.

The singing was generally up to the high standards that one might expect of such a prestigious production, with no real weak links. Tomlinson aside, one moment was outstanding: the scene in which Brünnhilde disrupts her forced wedding to Gunther by accusing Siegfried of treachery. Susan Bullock was sensational, turning the furies of hell onto anyone within earshot. I didn't feel that she hit the same heights throughout, with singing that was lovely to listen to without having quite that level of impact. Similarly, Stefan Vinke has the right voice for Siegfried - the voice of a young, impetuous man with great strength - but I did wish for a more commanding presence. Vinke's acting was excellent, however, with Siegfried portrayed as rather blundering, heroic in strength but too uncaring and, in spite of Brünnhilde's best efforts, too unintelligent to play a true hero's part in influencing events. Peter Coleman-Wright gave us an equally unintelligent and slightly fey Gunther, thoroughly credible as the self-important coward who is easy prey to Hagen's manipulation.

Generally, I loved the production. Acting performances were engaging throughout, and I found most of the visuals artistic and evocative. Stefanos Lazaridis's sets and Marie-Jeanne Lecca's costumes are of fairly indeterminate but basically modern period, but Warner isn't afraid to mix these with traditional props (sword, spear, rowing boat). The tarnhelm (the helmet which serves Siegfried both as shape-changer and teleporter) is a splendid creation: a Rubik's cube grid of darkened glass panels which echoes similar shapes in the Gibichungs' palace. Another spectacular effect is the fluoresecent red rope of fate, which picks up similarly fluorescent red markings in the three Norns' black robes. When Brünnhilde is brought in for the forced wedding, she is seated inside a ring of something barbed that immediately suggests the crown-of-thorns of suffering.

Wagner was a thoroughly cerebral composer who was much consumed by the philosophical and political concepts of his day. While he certainly wished to portray these concepts in his operas, you don't need to decode them in order to appreciate Götterdämmerung: the narrative is so strong that you can simply enjoy a master storyteller spinning an excellent yarn. Besides, it's hard to know for sure exactly which philosophical point Wagner is trying to make. Wagner himself was uncertain, and discarded no less than three different endings before settling on the one we know today: an orchestral tableau of the destruction of Valhalla viewed by silent watchers. Does this represent the destruction of capitalist tyranny by a Bakunin-inspired revolution? Or a Feuerbachian supplanting of theistic religion by some new humanist order? Or the destruction of the lesser races, to be replaced by a recreated world? We don't know for sure, and Wagner didn't want us to, deliberately discarding material that he considered too obvious. Warner seems to favour the last option, with a golden haired figure descending from the heavens within a giant steel ring, while naked Rhinemaidens cavort below - but I'm not entirely sure of Warner's intent either.

In truth, Götterdämmerung didn't challenge my intellect in the way Die Walküre did earlier in the cycle. But I was completely bewitched by the story and disarmed by the music. I think I'm joining the massed ranks of Ring fans.

Götterdämmerung, at Royal Opera HouseDavid Karlin reviews Götterdämmerung, the concluding part of Wagner's Ring Cycle, in Keith Warner's production at the Royal Opera House5