During Batman: Arkham Asylum The Riddler was more of a background villain who only popped in to challenge Batman to find every riddle that he had hidden around the island and if the player managed to do so they were treated to a bit of extra interaction between Batman and The Riddler, unfortunately he was never shown on screen.
But back at GDC Warner Brothers actually had shown off the Riddler in full view of everyone. This time around clues will only be visible by using detective mode and he has hidden trophies around the city similar to Arkham Asylum. At the same time players will be able to interrogate Riddler’s gang members and keep one of them partially concious so he can gather information on clues. This is a much better integration of The Riddler’s unique personality and challenges into a game than simply having questions appear out of thin air.