Jools' big band adds an extra dimension to this music.
It's always worth remembering that although pop songs (and this one's good anyhow) aren't written for big ensembles, there's no reason why a 'best possible' arrangement can't exist when all the resources pull together.
Yer old Glenn Miller style band stuff didn't always go post-impressionist with the brass dissonances, or favour minor keys and flattened intervals, because the old song style was romantic and major and happy, and the harder stuff appeared when the brass band had fallen out of favour, but it can revolutionise a song when all the tricks are pulled.
I hadn't heard this in ages, but back in 1999 I used to play this album *constantly*. I am not ordinarily a fan of his music, but Mutations is just outstanding. Maybe it's because Beck doesn't "rap" on this one.