I heard Jim took the role because he wanted to win the Academy Awards with his portrayal of a gay fraud artist. As usual, he put on his elastic comical face that didn't go down well with me.
On the other hand, Ewan's performance was a breakthrough. His acting was so natural, very convincing and funnily endearing as Jim's softer boyfriend. From other roles such as Obiwan Kinobi in Star Wars and to Moulin Rouge, he is really a very versatile actor. I would actually prefer him to win the award.
For those who are avid movie-goers, they would recognize Rodrigo as King Xerxes in the movie "300" on the Spartans.