You and I may be close in age. When I was in high school, I went through a punk/new wave phase, and then I became a full-on mod for several years. I never had a Vespa, but I had a parka, three-button jackets with narrow lapels, and skinny ties. And I listened to the Who, Kinks, Small Faces, American soul/R&B, and all that the Two Tone stuff. Plus a lot of ska/blue beat from the 1960s.
Quadrophenia I think is a really good film, and by far one of the best "rock" films. I rate it above Purple Rain or any of the Fabs' films. And from photos and archival footage I've seen, they really nailed the period.
I always wondered, though, about the scene in which the Mods crash the party and put the My Generation album on the hi-fi. Instead of showing the UK Brunswick LP cover, they show the 70s US MCA twofer reissue of My Generation/Magic Bus. I've wondered if that was a glaring continuity glitch, or if it was the Who's sly comment on the state of their US catalog.