"It was a very difficult decision to make, when I first heard about it I totally freaked at the idea," Farrell told Tarts. "But it was important to get Heath’s work out and doing what I think Heath would have wanted, which was finishing the movie to its entirety."
Just as the decision wasn’t easy for the Irish actor, it wasn't easy for the film's existing stars.
"I don’t know how I feel about it, Verne "Mini-Me" Troyer hesitantly told Tarts earlier this year. "Part of me thinks maybe it would be better to leave it be (and not replace Ledger)."
Source: Fox News