Why can't we have this?

You wouldn't guess it from the parade of ecstatic film stars, politicians and billionaires at the Walt Disney Hall's multiple openings last week, opulent as these events were with Botox, Versace and champagne, but this shining movie star of a building is the monument Los Angeles didn't know it wanted. This silver ship, with its curvaceous steel now shimmering in the balmy LA sunshine, was nearly scrapped before it was launched.

It is more than 15 years since Walt's widow Lillian pledged $50 million towards the building's cost (which would eventually be $274 million) and an international competition gave Frank Gehry, LA's greatest architect, his biggest project in his home city. In the ensuing decade-and-a-half the city's administrators and major donors have sucked their teeth and hummed and ha-ed. They thought about axing the project or letting it die a quiet death, or at least eviscerating its architect's intentions by handing it over to another to finish the job.

Then, in 1997, Gehry's Guggenheim Museum brought global stardom to the Basque city of Bilbao. Bilbao's name may not have been much murmured along Sunset Boulevard until then, but stardom is the sort of thing Los Angeles understands and the city's grandees finally came up with the money and the will to finish the job. Just as certain actresses have to prove themselves in European arthouse films before entering the Hollywood mainstream - Penelope Cruz, say - so did Gehry's architecture.

The result of this delay is that the Disney Hall lacks Bilbao's creative intensity, even if it is as beautiful (again, just like the transatlantic version of Penelope Cruz). Had it been built a decade ago, it would have been sensational, the first of its expressive, free-form kind. Instead it comes after a long line of lame knock-offs and wobbly wannabes. It is in danger of looking like a copy of itself, and some critics have marked it down as the tombstone of the whole wonky icon movement.

But perhaps its loss of shock value is a blessing, as it shifts attention to the fact that the building works. Usually there are two sorts of concert hall: those that look good and sound terrible, like the Royal Festival Hall, or those that look terrible and sound good, like Birmingham's Symphony Hall. It all depends on who has the biggest ego, the architect or the acoustician.

At the Disney's opening concert, from the first bars of the Star Spangled Banner, to the more demanding music of Stravinsky's Rite of Spring, it was obvious even to your cloth-eared critic that the place sounded beautiful, with a clean, clear acoustic that was digital rather than vinyl. At the same time, the aural experience could not be separated from the visual. Sound and vision combined to make this a deeply satisfying place to listen to music.

Some concert halls look like a collection of bits and pieces, with oddments of fabric and bent wood stuck together in response to the demands of acoustics and sight lines. With almost every surface clad in the same timber, Douglas fir, the Disney has the unity of a giant musical instrument. It also feels like a big, single room, intimate and grand at once. With the stage pushed out towards the middle, it binds performers and audience together in a single experience. On the inside the big steel ship becomes a Noah's Ark, a wooden haven floating on the swirl of freeways outside. It even allows in daylight, a blessing for the performers who spend long days in rehearsals.

At the end of the opening concert Gehry was called on stage three times to take the applause, alongside the Los Angeles Philharmonic's Finnish music director Esa-Pekka Salonen, and the acoustician Yasuhisa Toyota, a reflection of the collaboration between these three in making the place. On other projects they would be at each other's throats by this stage. At the Disney the display of harmony was convincing, and its results can be felt in the harmony of sound and look. You can also feel the influence of Gehry's friendship with musicians such as Pierre Boulez and Michael Tilson Thomas.

At the same time that Gehry was getting to know contemporary composers, he was also meeting the rather different culture of Walt Disney's legacy, in the shape of his widow and daughters. If Boulez is about nuance and paradox, Disney is about its opposite, about everything being exactly what it seems. The last time the names of Disney and Stravinsky came together it was for Fantasia, the 1940 animated film in which great music becomes the soundtrack for dancing hippos and long-lashed ponies whose cute soulfulness has, for me, an entirely emetic effect.

Gehry, however, is as positive about the Disneys as he is about new music. True, Lillian "brought me pictures of little thatched-roof brick cottages" to give her architect ideas, but she let him do things his own way. When the project was fighting for survival Walt's daughter Diane backed Gehry, because "she remembers the struggles her father went through, and saw that I was going through the same". Added to which $50 million is no small gift, even if you are as rich as the Disneys.