Director Tom Hooper's musical adaptation features an all-star group of actors, including Hathaway, Russell Crowe, Amanda Seyfried and Eddie Redmayne.
Speaking to OnTheRedCarpet, Hathaway revealed that she was particularly impressed by Hugh Jackman's dedication to the film.
"I love this cast - I am so blown away by everyone, especially Hugh," she declared, adding: "I mean, because we all love Hugh."
The actress continued: "Hugh is just the greatest guy in the world - but it's so great to see not only his dramatic chops, but his musical chops fuse and give a performance that I don't think anyone else in the world could have given.
"I'm so - I mean, I know it sounds weird because I'm younger than him, but I am so proud of him and I am so happy for him."
Hathaway recently expressed pride at having earned a Golden Globe nomination for her portrayal of Fantine in Les Misérables.
The film is showing in US cinemas now, and opens in the UK on January 11, 2013. Watch a trailer below: