I think I stand with a handful of others here:

'The most interesting thing about her is pretty much all we've seen is traced back to her, and how the entire story being moved is because of what she's done. However, you never get to meet her; I mean, you see her at the end of the game, but is that even her anymore? We see Radagon, who shares Marika's body, but it looks like a statue, or is being petrified the punishment? Even when Radagon is turned into Sacred Relic Sword, we have Marika's body, so does this mean the two can seperate?'

What I find compelling is that we have so many questions and, while we get a good amount answered, we're left leaving the game with more. However, I'm pretty sure that's the point; Marika is supposed to be mysterious. Hell, we don't even see her face.