The more I think about it, the more I wish that it were just the Joker and Alex. Having Lex there makes the Joker unnecessary. Luthor let the Joker do his thing, but he?d have done it himself if the Joker wasn?t there. It really should have been a little more drawn out in my opinion, with the Joker doing it all by his lonesome self, and Lex coming well after the fact or at most watching from great distance. Yes, it meant that Lex got to deliver some nasty lines. But he could have done them watching from a distance or just to Alex?s corpse. Really, I wish the Joker got one or two more scenes in the piece. Yes, he appeared back in issue #2 or so, wondering why he wasn?t part of the club. But it needed to be played up a bit in my opinion. The Joker is quite possibly the greatest fictional villain ever created, and while he wasn?t necessarily misused in Infinite Crisis, he certainly could have been better used.