During an interview with IGN the president of Ready At Dawn made it clear that Okami isn’t going to have any additional content except for motion control.
What new content appears in the game, compared to the PS2 version?
Didier Malenfant: The game on Wii is going to be an exact port of the PS2 version and I think that's what fans of the franchise want to see. This game has such a huge following throughout the world that people would probably send us death-threats if we messed it up by trying to add things that don't have their place in the Okami universe. Being huge fans of the franchise ourselves, we made sure that Capcom also wanted to stay true to the original before signing on to do this.
Okami is a personal favorite of mine so I can comprehend the “if it ain’t broke don’t fix it” mentality. However, as a fan I would have liked to get something new since I already own a copy of the game. A few extra stages with the realistic wolf from the earlier build of Okami would have fit the bill nicely. What do you think? Is motion control enough to warrant buying the Wii version?