I think that he is suave enough and has just the right amount of arrogance to pull it off. In fact, when I think of the Great Gatsby, I cannot think of any other actor that would be as fitting as Leonardo Dicaprio. Besides, he is very handsome and is able to adapt to many roles, including this one.
Yes, Leonardo has the most charm of any of the people who have played Gatsby. Leonardo is good looking, and has a flair matched to the role that none of the prior Gatsby actors were able to display. Other actors just seemed mismatched to have been cast in that role, but for Leonardo, the role was natural and captivating.
He is so iconic that you know him straight away but you see a totally different character contrasting to anything he's done before. This shows signs of brilliance which we know he has and therefore I could think of no one else to play Gatsby what so ever. Truly wonderful performance.