I never missed any replay options cuz there just isn't much that cant be done. Differing difficulties wouldn't work cuz there just isnt enough action, and for anything else, the format of the storytelling would have to change. Some new dialog would have sufficed. Or unlockable minigames, cuz there were virtually none.
Longer? Of course. But what I'd really have liked was more customizability in terms of his powers and stuff.