Based upon Reeve’s comments about corruption and the riddles we see left (referencing lies), as well as who we can deduce may be the victims due to the newspapers, I think we may be getting a Riddler who thinks himself a vigilante. I bet he will be killing corrupt government folks. I don’t see him as a Zodiac serial killer or a Seven style sadist. I think he may be portrayed a bit more sympathetic, while also disgusting in his methods. He may be leaving clues for Batman because he sees him as an ally in his crusade, or at least someone who shares his rancor toward corruption.
At least this is what I piece together from an interview and a 2 minute teaser trailer from a movie that’s only 25% complete.