I just saw it and liked it. Of course, I'm biased because I like David Chase for "The Sopranos" and Little Steven for you-know-what. Don't know how anyone else here will react if they check it out. The ending was weird and kind of sad, but I still liked it.
I saw shades of Tony Soprano in James Gandolfini's character, i.e. whenever he lost his temper, when he ate ice cream while watching TV, and when he worked the grill during a birthday barbecue. One big difference was that his standard of living was a lot more modest than Tony's. His wife in this movie reminded me of Tony's mother, i.e. really fucked in the head.
BTW, I thought Bella Heathcote was really cute, and the little sister of the band's lead singer blossomed quite nicely at the end.
I'll leave it up to everyone else to debate the authenticity of the band's clothing, hair styles, gear, and sound, along with the song choices for the soundtrack.