Donnie Darko is one of those movies, like Watchmen, that I really enjoyed first time I saw it but in the second viewing (usually the director's cuts) I wondered why I thought it was so great. As you know, I tend to find director's cuts a bit dragging if I'm not a die-hard fan of the original material. But in the case of The Butterfly Effect, the director's cut actually "repaired" a broken original theatrical release by restoring the original ending. IMO, directors cuts are best used to fix a film when the studio has done too much meddling or downright butchered what would otherwise be a good film. Interestingly enough, Francis Ford Coppola felt that the initial cut of The Godfather that Paramount Pictures wanted to release was too long and wanted to trim some of it down. But as it turns out Paramount's instincts were correct and it was originally released in the long version and became an all-time classic. But typical director's cuts tend to have the opposite problem with too many redundant or unnecessary scenes.