Long established character being unceremoniously killed for no reason other than shock value. Just another week in comics, amiright?

Though, Luthor's reaction does look pretty good. The idea that, despite how much he hates Superman, when he does something so terrible that even he's afraid of what's about to be brought down on him is kind of interesting. Kind of like the JLA cartoon when he "kills" Flash and for a moment is intimidated by Superman, knowing he's a hair away from being brutally killed.