I wasn't expecting much with it being a Video Game to Movie adaptation, but I think the actors really added something to it that couldn't have been added with not-well-known actors. I loved the references to their (Jack Black and Jason Mamoa's) other movies and the adult humor hidden in there. It added an element of je ne sais quoi. I think it was smart that they introduced the world and main character quickly to set the scene, rather than building the world slowly. A lot of smart moves for this movie and Jack Black's humor really nailed it home.