You all raise fine points about Byrne's WORLD'S FINEST cover commission. But I must say, I prefer it to some of his others because it looks like he at least worked on it a while. There is lots of detail there, even if you start noticing mistakes once you stare at it.
One recurring problem Byrne seems to have is the thick black marker (is it literally a Sharpie?) he uses for background art. The clouds of smoke on the WORLD'S FINEST sketch don't really work for me because they're too muddy compared to the rest of the scene. He recently posted a Teen Titans commission that showed the kids racing along the water, and likewise, he used the thick black marker to draw the waves, and it didn't work. At first glance, it looked like the Titans were running on a 1970s shag rug.