I could not be happier. Luthor has finally found his niche. This is the best thing to come out of New 52, because pre52 Luthor had done too many horrid things to be a hero, but new52 Luthor doesn't have that much baggage, so it's fine. I feel like this is where the character has been headed all this time and we didn't even know it, even after Straczynski predicted it in Supreme Power. I. Love. It.
I object to Luthor being on the Justice League. Captain Cold is even worse. For me, the Justice League will be Superman, Batman, Wonder Woman, Green Lantern (Hal), Flash, Aquaman, Cyborg, Shazam, and maybe Firestorm and Element Woman. If Luthor wants to start a Justice League, it should be Luthor, Joker, Cheetah, Sinestro, Captain Cold, Black Manta, Gizmo, and Black Adam.
Anyway, I'm more of a Justice League of Canada fan and let me just say that Jeff Lemire is amazing with the book.