It was all the things that everyone's said. My only quibble (and it's a small one) is that I think she really figured it out as Superman was telling her all about Luthor, and he was too wrapped up in the evidence he was presenting to notice her extra-wide eyes and jaw dropped even further, or he just chalked it up to her surprise at learning what Superman knew but couldn't prove.
I like the fact that she figured it out on her own. I also like her lack of anger with him for keeping such a secret. While having a second identity is a pretty big thing to keep from someone you claim to love, there aren't any laws to force him to reveal it. And up until the point where she confesses she knows the secret, he doesn't really know what she'd do with that information. So it works on any number of levels.
Stay evil, okay?
It's not all that bad, actually.
