When Metallica: Some Kind of Monster was released, hardcore metalheads wondered what it meant for a band like Metallica to not just pull back the curtain on the members' personal lives, but rip it down completely. All of a sudden the rockers known for their genre-defining thrash metal and industry-shaking record sales were paying $40,000 a month to have a therapist at their beck and call, filming every interaction they had over the course of three years.

With or without a documentary, though, Metallica faced significant PR issues in the early 2000s. Fans and critics wondered when the next studio album was going to be released. James Hetfield entered rehab for his alcohol addiction. Lars Ulrich turned into, as he puts it, "the most hated man in rock and roll" thanks to his involvement in trying to take down Napster. Oh, and Jason Newsted left the band.

Some Kind of Monster chronicled all of these things and more, giving fans a unique view into the creation of St. Anger, but more significantly, into the life of one of the biggest bands in the history of rock 'n' roll. Hetfield was open about how he hired a vocal coach in the '90s, even though he was scared he was going to have to sing "operatic;" all of the band members were clear that they didn't want to record another album like how they did Load and Reload; some of the lyrics on St. Anger's "Frantic" were inspired by, as Kirk Hammett explains, the Buddhist concepts of pain, life and death.

The list of revelations can go on and on, so we've narrowed it down to 10 unforgettable things we learned about Metallica after watching Some Kind of Monster. Even though it first premiered on Jan. 24, 2004, at the Sundance Film Festival, there are still new things fans—hardcore and new fans alike—can learn with each viewing.

10 Things We Learned About Metallica from 'Some Kind of Monster'

Metallica: Some Kind of Monster made its debut Jan. 24, 2004, at the Sundance Film Festival. Today, it holds an impressive 89 percent rating with critics 83 percent rating with fans on Rotten Tomatoes. The documentary puts Metallica in a never-before-seen light as the band members opened themselves up in incredibly vulnerable ways. With each viewing, there are still new things fans—hardcore and new fans alike—can learn about one of the biggest bands in the history of rock 'n' roll.

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